No-Fly Zones: Strategic, Operational, and
Legal Considerations for Congress
Jeremiah Gertler, Coordinator
Specialist in Military Aviation
Christopher M. Blanchard
Acting Section Research Manager
Stephen Daggett
Specialist in Defense Policy and Budgets
Catherine Dale
Specialist in International Security
Jennifer K. Elsea
Legislative Attorney
Richard F. Grimmett
Specialist in International Security
April 4, 2011
Congressional Research Service
7-5700
www.crs.gov
R41701
CRS Report for Congress
P
repared for Members and Committees of Congress
No-Fly Zones: Strategic, Operational, and Legal Considerations for Congress
Summary
In conflicts in Kosovo, Iraq, and Libya, the United States has taken part in establishing and
maintaining no-fly zones. As no-fly zones represent a significant commitment of U.S. forces, and
may prove a precursor to other military actions, Congress may wish to consider issues
surrounding the strategy, international authorization, congressional authorization, operations, and
costs of establishing and maintaining no-fly zones.
The military strategy designed to support U.S. grand strategy, it has been suggested, might be
based on these considerations: the operational-level military objectives that need to be achieved,
to support the overall grand strategy; and the extent to which a no-fly zone—as one set of ways
and means—helps achieve those objectives.
Practitioners and observers have debated what constitutes international “authorization” for the
establishment of a no-fly zone. Given the paucity of relevant precedents, and the dissimilarities
among them, there may not exist a single, clear, agreed model. The concept of authorization is
typically considered to be linked to the ideas of both “legality” and “legitimacy”—the three
concepts overlap but are all distinct. The precise meaning of each of the terms is still debated.
Express authorization from the U.N. Security Council provides the clearest legal basis for
imposing a no-fly zone.
In addition to international authorization, debates have addressed the question of congressional
authorization—whether and when there is a need for congressional approval based on the War
Powers Resolution for a proposed no-fly zone. The question of whether and how congressional
authorization is sought for a proposed operation could have an impact on congressional support—
including policy, funding, and outreach to the American people—for the operation. Since the War
Powers Resolution gives the President the authority to launch U.S. military actions prior to
receiving an authorization from Congress for 60-90 days, it is possible that the President could
direct U.S. Armed Forces to take or support military actions in accordance with U.N. Security
Council resolutions, or in support of NATO operations, and then seek statutory authority for such
actions from Congress.
No-fly zone operations can conceivably take a number of different forms, and can themselves
vary a great deal over time. Key considerations include, but are not limited to, the following
factors: the nature, density, quantity, and quality of adversary air assets; geography; the
availability of “friendly” assets; the adversary’s military capabilities and responses; the U.S.
military’s concept of operations; and the rules of engagement.
The costs of establishing and maintaining a no-fly zone are likely to vary widely based on several
key parameters. They could be the specific military tasks that a given no-fly zone operation calls
for, the geography of the adversary’s country, the duration of the no-fly zone, the extent to which
the United States is joined by international partners in the effort, and the extent of “mission
creep”—how, if at all, the operation expands to include a broader array of activities designed to
achieve the same military, and strategic, objectives.
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No-Fly Zones: Strategic, Operational, and Legal Considerations for Congress
Contents
Strategy ...................................................................................................................................... 1
Grand Strategy ...................................................................................................................... 1
Military Strategy ................................................................................................................... 1
Recent Cases......................................................................................................................... 2
International Authorization.......................................................................................................... 3
Law ...................................................................................................................................... 4
Legitimacy............................................................................................................................ 5
Recent Cases......................................................................................................................... 5
Congressional Authorization ....................................................................................................... 6
Operations .................................................................................................................................. 8
The Situation ........................................................................................................................ 8
The Nature and Density of Adversary Air Defenses ......................................................... 8
The Quantity and Quality of Adversary Air Assets........................................................... 8
Geography ...................................................................................................................... 8
Availability of “Friendly” Assets ..................................................................................... 9
The Adversary....................................................................................................................... 9
The Adversary’s Strategy and Tactics .............................................................................. 9
The Adversary’s Responses ............................................................................................. 9
Concept of Operations..................................................................................................... 9
Rules of Engagement .................................................................................................... 10
Costs......................................................................................................................................... 10
Additional CRS Reports............................................................................................................ 11
Tables
Table 1. Costs of Selected U.S. Combat Air Operations, FY1993-FY2003................................. 12
Contacts
Author Contact Information ...................................................................................................... 13
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No-Fly Zones: Strategic, Operational, and Legal Considerations for Congress
Strategy1
Many diplomatic and military practitioners as well as theorists have argued that successful
execution of a military operation depends on the how well specific actions are matched to
strategic intent.2
Grand Strategy
It has been argued that the imposition of any no-fly zone, a particular form of military operation,
should begin with a clear articulation of strategic-level goals. For any given situation, such “grand
strategy” might include, in this order:
• a clear statement of the U.S. national interests at stake;
• a vision of the political endstate—the strategic-level outcomes—that would help
secure those interests;
• a clear articulation of the major steps—the ways and means—including
diplomatic, political, and economic as well as military, to be employed in order to
accomplish the desired endstate, including the objectives each is designed to
achieve; and
• a consideration of the nature and extent of political “risk” in the proposed
approach—including the potential impact of proposed actions on the civilian
population in the targeted country, on the region, on broader international
partnerships, and on perceptions of the U.S. government both at home and
abroad.
Military Strategy
The military strategy designed to support the grand strategy, it has been suggested, might be
based on these considerations:
• the operational-level military objectives that need to be achieved, to support the
overall grand strategy, and
• the extent to which a no-fly zone—as one set of ways and means—helps achieve
those objectives. Recent operational experiences suggest that the establishment of
a no-fly zone, in itself, is unlikely to achieve the full set of military objectives,
such as protecting a civilian population, let alone the grand strategic objectives,
such as restoring or removing a regime.
1 This section was prepared by Catherine Dale, Specialist in International Security, and Jeremiah Gertler, Specialist in
Military Aviation.
2 Prussian writer Carl von Clausewitz argued, “No one starts a war, or rather, no one in his senses ought to do so,
without first being clear in his mind what he intends to achieve by that war and how he intends to conduct it.” See Carl
von Clausewitz, On War, translated by Michael Howard and Peter Paret, Princeton, NJ: Princeton University Press,
1976.
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Recent Cases
In key recent “no-fly zone” cases, observers suggest that the strategic planning process may have
emphasized “mid-range” operational-level concerns at the expense of higher-level strategic
concerns. In Operation Odyssey Dawn, Operation Northern Watch, Operation Southern Watch,
and Operation Deny Flight, the match between the application of one military approach—the no-
fly zone—and broad strategic goals, many assess was at best incomplete.3
Operation Odyssey Dawn, a coalition operation conducted during early 2011 over Libya, was put
in place to enforce United Nations Security Council Resolution 1973, which authorized force to
protect civilians in Libya. Facing a popular uprising, the Libyan government under Muammar al
Qadhafi had responded with attacks against population centers with armor, artillery, and air
strikes. Going beyond a pure no-fly zone, Operation Odyssey Dawn prevented Libyan air forces
from operating against civilians, while including attacks against pro-Qadhafi ground forces that
were perceived to be threatening civilian populations.
Operation Northern Watch (ONW), a combined operation involving U.S., UK, and French forces
conducted from 1991 to 2003 in Iraq, was designed to enforce a no-fly zone in northern Iraq,
north of the 36th parallel, in order to prevent Iraqi repression of the concentrated ethnic Kurdish
population living in that part of the country.4 The Iraqi government led by Saddam Hussein had
already made use of Iraqi airspace to attack Iraqi Kurds in Halabja with chemical weapons in
1988. Acts of repression after the conclusion of the early 1991 Gulf War had displaced many Iraqi
Kurds. The immediate aim of ONW was to protect the population from further attacks by the
Iraqi military, and it is generally considered that ONW largely achieved this operational objective.
At the strategic level, ONW took place against the backdrop of international pressure on the Iraqi
government to comply with an international weapons inspection regime, in accordance with U.N.
Security Council resolutions. Missing from ONW, in any explicit way, was a vision of political
endstate, or a stated theory of the case linking the no-fly zone to that endstate.
Similarly, Operation Southern Watch (OSW), a U.S.-led coalition operation, was designed to
protect the Shi’a Arab population of southern Iraq from repression and retaliation by Iraqi
government forces in the wake of the Gulf War. The Iraqi government had made use of its own
airspace to conduct bombing and strafing runs targeting Shiite citizens. In terms of immediate
operational objectives, OSW is generally considered not to have prevented Iraqi government
repression of its southern population. At the strategic level, while some U.S. officials had
reportedly considered, at one time, that in the wake of the Gulf War southern Iraqi Shiites might
rise up to demand the ouster of Saddam’s regime, OSW does not appear to have been guided by
any explicit vision of political endstate.
Operation Deny Flight (ODF) was a NATO operation that banned all flights—with some
exceptions—in the airspace of Bosnia and Herzegovina from April 1993 to December 1995. The
military objectives included denying the use of that airspace to Bosnian Serb aircraft, in order to
protect the population and facilitate the delivery of humanitarian assistance. Observers have
3 For assessments of these cases, see Joshua Keating, “Do No-Fly Zones Work?” Foreign Policy, February 28, 2011;
and Alexander Benard, “Lessons from Iraq and Bosnia on the Theory and Practice of No-Fly Zones,” The Journal of
Strategic Studies Vol.27, No.3, September 2004, pp.454-478.
4 The mission was originally called Operation Provide Comfort; the name Operation Northern Watch was adopted in
1997.
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debated the ODF’s degree of success in this regard—while humanitarian work by international
relief organizations was protected to some extent, Bosnian Serb aircraft periodically defied the
flight ban to stage attacks, while on the ground, for example, Bosnian Serb forces overran the
U.N. safe haven in Srebrenica, in 1995, killing thousands. At the strategic level, ODF may have
come closer than the no-fly zone operations in Iraq to linkage with strategic objectives. In the
preamble of the 1992 U.N. Security Council resolution authorizing ODF’s precursor, a no-fly
zone banning military aircraft, the Council “consider[ed] that the establishment of a ban on
military flights in the airspace of Bosnia and Herzegovina constitutes an essential element for the
safety of the delivery of humanitarian assistance and a decisive step for the cessation of hostilities
in Bosnia and Herzegovina.”5 Some experts believe that the Bosnian no-fly zone contributed
directly to the ultimate cessation of hostilities; others suggest that its contribution is difficult to
separate from the roles of close air support and the ground presence of U.N. troops. There is little
evidence to suggest that a clear and specific vision of the political endstate that might follow a
cessation of hostilities informed the creation of the no-fly zone.
Operation Odyssey Dawn was a U.S. operation supporting a NATO resolution to protect civilians
during the Libyan civil war in March 2011. Although Odyssey Dawn included establishment and
enforcement of a no-fly zone, it also included strike operations against Libyan government forces
perceived to be attacking civilian populations, and the command and control and logistics
networks supporting those forces. More information on Operation Odyssey Dawn can be found in
CRS Report R41725, Operation Odyssey Dawn (Libya): Background and Issues for Congress.
International Authorization
Practitioners and observers have debated what constitutes international “authorization” for the
establishment of a no-fly zone. Given the paucity of relevant precedents, and the dissimilarities
among them, there may not exist a single, clear, agreed model.
Authorization may be not only a question of approval or disapproval. It may also include
• parameters for the execution of the mission, and
• conditions under which the authorization for the no-fly zone operation will be
considered discontinued. It may not be necessary to achieve all of the broad
objectives of grand strategy before discontinuing the no-fly zone—the no-fly
zone operation may be designed to catalyze overall progress toward those
objectives.
In turn, the concept of authorization is typically considered to be linked to the ideas of both
“legality” and “legitimacy”—the three concepts overlap but are all distinct. The precise meaning
of each of the terms is still debated.
5 U.N. Security Council Resolution 781 (1992), October 9, 1992.
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Law6
The legality of a no-fly zone operation may depend, at a minimum, on both authorization for the
operation and the extent to which the manner of execution of the operation comports with
relevant international law.
The Charter of the United Nations, in Article 2(4), prohibits the “threat or use of force against the
territorial integrity or political independence” of a member state under most circumstances, and
many practitioners and observers have wondered whether the establishment of a no-fly zone
would constitute a violation of this prohibition.7 In practice, the answer may depend on the
circumstances—and in some cases there may be no general agreement about what the empirical
circumstances indicate. There are at least three sets of circumstances that do—or may—constitute
exceptions to this prohibition.
The first basis for an exception is U.N. Security Council authorization based on the powers
granted to the Council by Chapter VII of the U.N. Charter to respond to threats to international
peace and security. That Chapter authorizes the Security Council to “determine the existence of
any threat to the peace, breach of the peace, or act of aggression” and to “make recommendations,
or decide what measures shall be taken ... to maintain or restore international peace and security.”
Express authorization from the Security Council provides the clearest legal basis for imposing a
no-fly zone.
The second basis for an exception is self-defense. Article 51 of the Charter explicitly recognizes
the right of self-defense as an exception to the prohibition. The Article states, “Nothing in the
present Charter shall impair the inherent right of individual or collective self-defense if an armed
attack occurs against a Member of the United Nations.”
Some theorists and practitioners consider that there also exists a customary doctrine of self-
defense outside of the U.N. Charter that permits military action to prevent a grave threat to
regional peace and stability, even if that threat seems to be contained within the borders of a state.
According to this view, armed intervention within a state is not a prohibited “use of force” so long
as it is not aimed at taking a state’s territory or subjecting its people to political control (a narrow
reading of “use of force against the territorial integrity or political independence of any State”),
and is not otherwise inconsistent with the intent of the U.N. Charter. If this reading is correct,
then customary measures of self-help involving the use of force but falling short of war—
reprisals, embargoes, boycotts, temporary occupations of foreign territory, pacific blockades, and
similar measures—are not precluded by the U.N. Charter, but are acceptable means of customary
self-defense preserved by Article 51. Others contend, however, that the Article 51 limitation
supersedes what had been customary international law in these matters, and that the established
practice of use of force by states in response to provocations other than armed attacks does not
establish valid precedent, but rather, violates the Charter.
6 This section was prepared by Jennifer Elsea, Legislative Attorney.
7 The U.N. Charter, 59 Stat. 1031, states in its preamble that one of its purposes to be “to save succeeding generations
from the scourge of war,” and in Article 2(4) it requires its Members “to refrain from the threat or use of force against
the territorial integrity or political independence of any State, or in any other manner inconsistent with the Purposes of
the United Nations.”
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Third, some have argued that emerging international human rights law provides that states are no
longer free to treat their people as they see fit under the guise of sovereignty, but are instead
obligated to respect their people’s fundamental human rights. When a government engages in
widespread abuse of the human rights of its own people, it has been asserted, that government
loses a measure of its sovereignty. Other states, the argument continues, have the right or even the
responsibility to intervene in order to put a stop to crimes against humanity, as an extension of the
customary right of self-defense or the defense of others. This emerging doctrine of humanitarian
intervention—sometimes described as the “responsibility to protect”—is not yet fully developed
in international law, and there is no consensus about its application, including whether it
constitutes an exception to the prohibition on the “threat or use of force.” Some believe that only
the U.N. Security Council has the authority to invoke this doctrine.
The question of international authorization has direct implications, in turn, for the state in which a
no-fly zone is imposed. If a no-fly zone is imposed against a state that has not carried out an
armed attack against another state, in the absence of U.N. authorization based on Chapter VII of
the U.N. Charter, and depending on the form the no-fly zone operation takes, that state might be
entitled to consider the imposition of the no-fly zone itself an “armed attack.” Even if the no-fly
zone operations in a given state do not constitute an “armed attack”—which in itself may be a
subjective judgment—that state, and other members of the international community, might
consider them a violation of the prohibition of the “threat or use of force,” as well as of the
customary duty of non-intervention in the affairs of other sovereign states. The state targeted by
the no-fly zone might, on that basis, choose to respond with military force or to seek assistance
from its allies or partners to assist in its self-defense.
Legitimacy
While the legitimacy of any no-fly zone operation may draw on both authorization and legality,
legitimacy is by definition a subjective question of perception—by the people of the host nation,
by the U.S. population, and by other members of the international community. Issues to consider
may include
• how the nature and extent of international authorization is likely to shape the
perceived legitimacy of the no-fly zone operation;
• how the conduct of the operation is likely to shape that perceived legitimacy;
• the extent to which that perception of legitimacy, in turn, is likely to shape the
support of members of the international community for the effort—ranging from
political support, to the provision of basing, access, and overflight privileges, to
full participation; and
• the extent to which perceived legitimacy is likely to affect the international
community’s broader perceptions of, and support for, other concurrent or future
U.S. initiatives.
Recent Cases
The most germane recent no-fly zone cases do not establish a clear model for securing
international authorization—they differ from one another, and in some instances they have
spurred debate rather than consensus about what constitutes appropriate authorization.
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Both Operation Northern Watch (ONW) and Operation Southern Watch (OSW) were established
in the wake of the early 1991 Gulf War in order to protect civilian populations of Iraq—ethnic
Kurds living in northern Iraq, and Shi’a Arabs living in southern Iraq, respectively—from
repression by the Iraqi government and its forces. In April 1991, in U.N. Security Council
Resolution 688 (1991), the Council “condemn[ed] the repression of the Iraqi civilian population
... the consequences of which threaten international peace and security in the region.” While that
resolution strongly encouraged humanitarian action and urged member states to support it, it
made no mention of military action.8 The previous November, the Council had laid the
groundwork for military action in Iraq—the authorization for Gulf War operations—in U.N.
Security Council Resolution 678 (1990), which invoked Chapter VII of the U.N. Charter. The
resolution demanded that Iraq comply with previous resolutions, gave Iraq “one final
opportunity” to do so, and—failing Iraqi compliance—“authorize[d] Member States ... to use all
necessary means to uphold and implement [past Resolutions] and to restore international peace
and security in the area.”9 Experts and practitioners have since hotly debated the applicability of
the November 1990 blanket authorization to “use all necessary means” to the two operations that
followed the Gulf War proper.
Operation Deny Flight, designed to protect the civilian population of Bosnia and Herzegovina,
was based on a clear-cut U.N. mandate, although there may be less consensus about the basis for
its precursor operation. In October 1992, in U.N. Security Council Resolution 781 (1992), the
Council established a “ban on military flights in the airspace of Bosnia and Herzegovina,”
primarily on humanitarian grounds, to help ensure the safe delivery of humanitarian assistance.10
Following repeated violations of that ban, in March 1993 the Council invoked Chapter VII of the
Charter, extended the ban, and “authorize[d] Member States ... acting nationally or through
regional organizations or arrangements, to take ... all necessary measures in the airspace of the
Republic of Bosnia and Herzegovina, in the event of further violations, to ensure compliance with
the ban on flights.”11
Congressional Authorization12
In addition to international authorization, debates have addressed the question of congressional
authorization—whether and when there is a need for congressional approval based on the War
Powers Resolution for a proposed no-fly zone. The question of whether and how congressional
authorization is sought for a proposed operation could have an impact on congressional support—
including policy, funding, and outreach to the American people—for the operation.
On November 7, 1973, Congress passed the War Powers Resolution, P.L. 93-148, over the veto of
President Nixon. The War Powers Resolution (WPR) states that the President’s powers as
Commander in Chief to introduce U.S. forces into hostilities or imminent hostilities can only be
exercised pursuant to (1) a declaration of war; (2) specific statutory authorization; or (3) a
national emergency created by an attack on the United States or its forces. It requires the
8 U.N. Security Council Resolution 688 (1991), April 5, 1991.
9 U.N. Security Council Resolution 678 (1990), November 29, 1990.
10 U.N. Security Council Resolution 781 (1992), October 9, 1992.
11 U.N. Security Council Resolution 816 (1993), March 31, 1993.
12 This section was prepared by Richard Grimmett, Specialist in International Security.
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President in every possible instance to consult with Congress before introducing American Armed
Forces into hostilities or imminent hostilities unless there has been a declaration of war or other
specific congressional authorization. It also requires the President to report to Congress any
introduction of forces into hostilities or imminent hostilities, Section 4(a)(1); into foreign territory
while equipped for combat, Section 4(a)(2); or in numbers which substantially enlarge U.S. forces
equipped for combat already in a foreign nation, Section 4(a)(3). Once a report is submitted “or
required to be submitted” under Section 4(a)(1), Congress must authorize the use of force within
60 to 90 days or the forces must be withdrawn. Since the War Powers Resolution’s enactment in
1973, every President has taken the position that this statute is an unconstitutional infringement
by Congress on the President’s authority as Commander in Chief. The courts have not directly
addressed this question, even though lawsuits have been filed relating to the War Powers
Resolution and its constitutionality.
Some recent operations—in particular U.S. participation in North Atlantic Treaty Organization
(NATO) military operations in Kosovo, and in U.N.-authorized operations in Bosnia and
Herzegovina, in the 1990s—have raised questions concerning whether NATO operations and/or
U.N.-authorized operations are exempt from the requirements of the War Powers Resolution.
Regarding NATO operations, Article 11 of the North Atlantic Treaty states that its provisions are
to be carried out by the parties “in accordance with their respective constitutional processes,”
implying that NATO Treaty commitments do not override U.S. constitutional provisions
regarding the role of Congress in determining the extent of U.S. participation in NATO missions.
Section 8(a) of the War Powers Resolution states specifically that authority to introduce U.S.
forces into hostilities is not to be inferred from any treaty, ratified before or after 1973, unless
implementing legislation specifically authorizes such introduction and says it is intended to
constitute an authorization within the meaning of the War Powers Resolution.
Regarding U.N.-authorized operations, for “Chapter VII” operations, undertaken in accordance
with Articles 42 and 43 of the U.N. Charter, Section 6 of the U.N. Participation Act, P.L. 79-264,
as amended, authorizes the President to negotiate special agreements with the U.N. Security
Council, subject to the approval of Congress, providing for the numbers and types of armed
forces and facilities to be made available to the Security Council. Once the agreements have been
concluded, the law states, further congressional authorization is not necessary. To date, no such
agreements have been concluded.
Given these provisions of U.S. law, and the history of disagreements between the President and
the Congress over presidential authority to introduce U.S. military personnel into hostilities in the
absence of prior congressional authorization for such actions, it seems likely that a presidential
effort to establish a “no-fly zone” on his own authority would be controversial. Controversy
would be all the more likely if the President were to undertake action “pre-emptively” or in the
absence of a direct military threat to the United States.
Since the War Powers Resolution gives the President the authority to launch U.S. military actions
prior to receiving an authorization from Congress for 60-90 days, it is possible that the President
could direct U.S. Armed Forces to take or support military actions in accordance with U.N.
Security Council Resolutions, or in support of NATO operations, and then seek statutory
authority for such actions from Congress.
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Operations13
No-fly zone operations can conceivably take a number of different forms, and can themselves
vary a great deal over time. Key considerations include, but are not limited to, the following
factors.
The Situation
The Nature and Density of Adversary Air Defenses
The sophistication of air defenses varies widely around the world, from individual, poorly-
coordinated anti-aircraft guns to integrated air defense networks coupled with high-performance
surface-to-air missile systems and modern fighter aircraft. The characteristics of a given air
defense system will indicate whether establishing a no-fly zone requires that the defenses be
destroyed, suppressed (by jamming, network attack, or other means), or merely bypassed. It will
also dictate in part the tactics required for the initial suppression of enemy air defenses—for
example, whether it can best be done by manned aircraft, standoff weapons such as cruise
missiles, and/or remotely-piloted aircraft (also known as unmanned aerial vehicles or “UAVs”).
The Quantity and Quality of Adversary Air Assets
The size of the air component to be suppressed—not only the number of aircraft, but also bases—
also informs the capabilities that the U.S. and partner forces would have to bring to bear. The
quality of the air assets—particularly the quality and training of fighter forces, and the
effectiveness of their command and control system—affects the amount of defensive assets that
would have to be included in the no-fly zone force package, as well as the balance of efforts
dedicated to offensive action against the enemy, and to defensive action to enhance the survival of
“friendly” forces.
Geography
The geographical boundaries of a no-fly zone help define both the relevant assets and the level of
suppression of enemy air defenses (SEAD) required. For example, a no-fly zone focused on
coastal areas could allow “friendly” naval air assets to engage more readily, and may not require
the same level of SEAD as a no-fly zone that requires tactical aircraft (and especially supporting
assets like tankers) to penetrate deeply into the defended airspace. Similarly, a no-fly zone that
denies flight only over major urban areas, for example, reduces the resource requirements for the
no-fly zone compared to denial of air activity over a whole country, as in Bosnia and
Herzegovina; or major areas of a country, as in northern and southern Iraq. The proximity of
allied and partner states can affect the availability of basing for land-based tactical aircraft and
UAVs—the negotiation of new agreements regarding basing, access, and overflight, if required,
can take time. The proximity of oceans, in turn, can provide navigable waters for carrier-based
aircraft and/or cruise missile-equipped ships.
13 This section was prepared by Jeremiah Gertler, Specialist in Military Aviation.
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Availability of “Friendly” Assets
Plans for resourcing a no-fly zone may be shaped by concurrent or potential competing demands,
in particular for “high-demand, low-density” assets such as intelligence, surveillance, and
reconnaissance (ISR). For example, U.S. ISR assets supporting the war effort in Afghanistan have
been increased substantially, in part by drawing some assets away from Iraq; but the demand
continues to grow.
The participation of allies and partners can reduce the demands on U.S. forces for some
capabilities—for example, strike—but depending on the scenario, the capabilities of partners in
areas such as surveillance, and command and control, may not be sufficiently robust to provide
equivalent effectiveness.
The Adversary
The Adversary’s Strategy and Tactics
Strategists generally argue that an understanding of the adversary’s strategy and likely tactics
should help inform the operational-level objectives of a no-fly zone operation. That
understanding may be based in part on precedent—for example, the Iraqi government’s use of
chemical weapons against its own northern Kurdish population in 1988, and its use of fixed-wing
and rotary-wing aircraft to strafe the population in southern Iraq after the Gulf War. That
understanding may also be informed by current intelligence based on input from a variety of
possible platforms and assets. If the adversary uses a large fixed-wing transport fleet to move
troops around the country, or if it has a large concentration of fighter aircraft near a border with
an ally or partner in the region and a track record of some hostility with that state, these factors
may shape the priorities of the no-fly zone operations.
The Adversary’s Responses
Operational planning for a no-fly zone is likely to consider the adversary’s most likely and most
dangerous responses to the operation. Expectations—and intelligence—concerning possible
adversary responses may shape the planned conduct of the operation, including the scope and
scale of capabilities brought to bear.
Concept of Operations
If denying the adversary’s fixed-wing operations is sufficient to achieve the desired operational-
and strategic-level effects, “air caps” can be maintained over the adversary’s air bases, or standoff
weapons can be used to render runways unusable, with minimal risk of civilian casualties or other
loss. Minimizing the force used—for example, choosing not to destroy aircraft on the ground,
hangars, or other support facilities—may allow a more rapid return to operation after the
conclusion of the no-fly zone effort; this may be an important consideration, depending on the
desired overall political endstate.
If, on the other hand, the operational-level goals include denying adversary rotary-wing
operations, a more significant no-fly zone operation would be necessary. Interdicting physical
facilities—hangars, runways, ramp areas—has a much more limited effect on rotary-wing
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operations. Because helicopters are not tied to large bases, they are harder to locate when on the
ground, requiring more assets to detect them and to monitor potential changes of location.
Helicopters are also harder to detect than fixed-wing aircraft when airborne, particularly if the
operators are skilled in using nap-of-the-earth flight and other techniques to minimize visibility to
radar.
Destruction of rotary-wing assets in the air would typically require getting within closer range of
the targets than for fixed-wing platforms. Helicopters are harder to hit as well as to detect. In a
scenario requiring suppression of rotary-wing activity, merely suppressing coastal or local air
defenses would not be sufficient; since the helicopters could be almost anywhere in the
adversary’s territory, access to the adversary’s full airspace would be necessary.
Rules of Engagement
Those imposing a no-fly zone operation may choose to limit it formally in scope, in the area of
operation, in allowable weapons and tactics, or in other ways, in order to avoid civilian casualties
or other loss, to incentivize defections by adversary forces, to restrict actions likely to alienate
partners, or for other strategic considerations.
Costs14
The costs of establishing and maintaining a no-fly zone are likely to vary widely based on several
key parameters:
• the specific military tasks that a given no-fly zone operation calls for. For
example, initial costs might be relatively high if, as a first step, it were necessary
to destroy the adversary’s air defenses. A particularly robust surface-to-air
capability, including a large number of discrete SAM sites, might prove relatively
costly to suppress.
• the geography of the adversary’s country—the surface area and type of terrain
over which U.S. and partner forces would have to operate. A large surface area,
as in ONW and OSW in Iraq, or mountainous terrain, as in ODF in Bosnia and
Herzegovina, could both add cost, depending on the concept of operations for
enforcing the no-fly zone.
• the duration of the no-fly zone.
• the extent to which the United States is joined by international partners in the
effort.
• the extent of “mission creep”—how, if at all, the operation expands to include a
broader array of activities designed to achieve the same military, and strategic,
objectives.
As a rough guide to the range of possible costs, Table 1 shows the costs to the U.S. government
of U.S. participation in a variety of air operations in the 1990s. Of these, Operation Noble Anvil,
the air war in Yugoslavia designed to address conflict in Kosovo, was the most intense. It
14 This section was prepared by Stephen Daggett, Specialist in Defense Policy and Budgets.
Congressional Research Service
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No-Fly Zones: Strategic, Operational, and Legal Considerations for Congress
involved initially limited and later extensive attacks to degrade air defenses throughout the
Federal Republic of Yugoslavia, including all of Serbia. Those were followed by escalating air
attacks initially focused on the military infrastructure and later on strategic targets. The operation
lasted for two and a half months, from March 24 through June 10, 1999. The operation—
including the no-fly zone and extensive additional activities—cost a total of $1.8 billion.
Toward the other end of the spectrum are costs of the two no-fly zone coalition operations in Iraq.
The costs to the U.S. government of Operation Southern Watch averaged somewhat more than
$700 million per year, although the amounts varied substantially from year to year. The OSW
mission involved constant patrols over a relatively large geographic area, punctuated by
occasional strikes against Iraqi air defense sites. It imposed a considerable burden on U.S. Air
Force units, mainly because of the long duration of the operation—from 1992 to 2003.
Additional CRS Reports
CRS Report RL31133, Declarations of War and Authorizations for the Use of Military Force:
Historical Background and Legal Implications, by Jennifer K. Elsea and Richard F. Grimmett.
CRS Report R41199, The War Powers Resolution: After Thirty-Six Years, by Richard F.
Grimmett.
CRS Report RS20775, Congressional Use of Funding Cutoffs Since 1970 Involving U.S. Military
Forces and Overseas Deployments, by Richard F. Grimmett.
CRS Report RS21311, U.S. Use of Preemptive Military Force, by Richard F. Grimmett.
Congressional Research Service
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No-Fly Zones: Strategic, Operational, and Legal Considerations for Congress
Table 1. Costs of Selected U.S. Combat Air Operations, FY1993-FY2003
(amounts in millions of current year dollars)
FY1993 FY1994 FY1995 FY1996 FY1997 FY1998 FY1999 FY2000 FY2001 FY2002 FY2003
Southwest Asia
Provide Comfort/Northern Watch
325.0
101.5
116.6
91.8
138.2
88.9
93.1
136.0
156.4
143.7
138.7
Southern Watch/Air Expeditionary Force
715.9
333.0
468.4
576.3
597.3
1,497.2
933.2
755.4
678.0
Desert
Fox
(Air
Strikes,
Dec.
1998)
92.9
Former Yugoslavia (Kosovo)
Balkan
Calm
(Observer
Mission,
Pre-Air
War)
34.6
Eagle Eye (Air Verification, Oct. 1998-Mar. 1999)
20.3
Noble Anvil (Air War)
1,775.7
Source: CRS based on data provided by Department of Defense, Office of the Under Secretary of Defense Comptrol er.
CRS-12
No-Fly Zones: Strategic, Operational, and Legal Considerations for Congress
Author Contact Information
Jeremiah Gertler, Coordinator
Catherine Dale
Specialist in Military Aviation
Specialist in International Security
jgertler@crs.loc.gov, 7-5107
cdale@crs.loc.gov, 7-8983
Christopher M. Blanchard
Jennifer K. Elsea
Acting Section Research Manager
Legislative Attorney
cblanchard@crs.loc.gov, 7-0428
jelsea@crs.loc.gov, 7-5466
Stephen Daggett
Richard F. Grimmett
Specialist in Defense Policy and Budgets
Specialist in International Security
sdaggett@crs.loc.gov, 7-7642
rgrimmett@crs.loc.gov, 7-7675
Congressional Research Service
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