March 10, 2022
What Is a No-Fly Zone (NFZ)?
A “No-Fly Zone” (NFZ) is a military operation to ensure
fighter escorts, thereby increasing the overall quantity of
that no aircraft operate in the airspace of a defined
fighter aircraft.
geographic area. An NFZ could also suppress and/or
destroy air defenses in a defined region. Many defense
In order to coordinate a large and complex operation, the
analysts consider maintaining NFZs to be combat
NFZ may require battle management aircraft such as the E-
operations, likely involving actively shooting down and/or
3 Airborne Warning and Control System (AWACS). The E-
destroying a hostile country’s aircraft, therefore requiring
3 is a strategically important aircraft that also has minimal
rules of engagement detailing how and when forces can
defenses. To fly in contested airspace (which would allow it
engage a violating aircraft. NFZs are generally international
to provide the full range of capabilities of its radar), it
operations, and U.S. participation in them entails oversight
would also likely need fighter escorts. Alternatively,
and funding considerations by Congress.
AWACS could operate further away. While this would
make defending AWACS aircraft easier, this would mean
The United States has participated in four declared NFZ
that they would not be able to provide as comprehensive
operations:
radar coverage as they might if they operated within
contested airspace.
Operation Deny Flight, from 1993 to 1995, over Bosnia
and Herzegovina;
Suppression of Enemy Air Defense (SEAD) missions in an
Operation Northern Watch, from 1991 to 2003, over the
NFZ would likely require additional combat aircraft. First,
36th Parallel over Iraq;
electronic attack aircraft like the EA-18 Growler and the
Operation Southern Watch, from 1992 to 2003, over the
EC-130 Compass Call would need to provide electronic
32nd Parallel (later extended to the 33rd Parallel) over
warfare capabilities to interfere or “jam” active radar
Iraq; and
signals. These aircraft could also identify radar and surface-
Operation Odyssey Dawn, in 2011, over Libya.
to-air missile locations. Should air defenses become active,
What Is Required for an NFZ?
EA-18 Growlers and F-16CMs could launch Advanced
To establish an NFZ, military forces need to commit to
Antiradiation Guided Missiles to destroy active radars, thus
enforcing the NFZ and potentially engaging in combat
preventing missiles from receiving targeting data.
against violators. Military planners generally assume that
the airspace in an NFZ would be militarily contested, at
In addition, the military would plan for combat search and
least initially, and that friendly forces may need to establish
rescue (CSAR) personnel and assets to potentially recover
air superiority before enforcing an NFZ. Maintaining an
U.S. or allied pilots shot down or crashing due to
NFZ, therefore, requires a significant amount of military
mechanical failure while enforcing the NFZ. Such assets
combat forces, usually aircraft. Ground-based air defense
were utilized in the Balkans when an F-117 and an F-16
assets might also be used to implement an NFZ, either on
were shot down by Serbian air defenses.
their own or in conjunction with aircraft. Ground-based air
defense assets have tactical limitations, due in part to their
Unmanned aircraft might be able to provide support in an
range as well as their ability to engage relatively fewer
NFZ. Such unmanned aircraft (e.g., RQ-4 Global Hawk,
adversary aircraft over the area designated as an NFZ.
MQ-9 Reaper, and the MQ-1C Gray Eagle) could detect
However, ground-based air defense systems can be less
potential violating aircraft or air defenses, as well as
resource-intensive than maintaining air patrols in an air-
support SEAD and electronic warfare missions. Unmanned
enforced NFZ.
aircraft could also be used as decoys to potentially “bait” an
adversary to attack and expend limited resources, as when
For any NFZ involving aircraft, a military needs to deploy
the U.S. Air Force used MQ-1 Predators in Operations
and maintain a sufficient number of combat fighters to
Northern and Southern Watch.
maintain control of the airspace. A military conducting the
NFZ would most likely arm fighter aircraft with air-to-air
Military Planning Considerations
missiles in order to engage any aircraft violating the NFZ
Planning for an NFZ includes consideration of adversary air
airspace. Due to the relatively short ranges of fighter
defenses, quantity and quality of adversary aircraft,
aircraft, aerial refueling aircraft like the KC-135
geography, availability of friendly assets, adversary strategy
Stratotanker, the KC-10 Extender, and the KC-46 Pegasus
and tactics, and rules of engagement.
would likely fly within contested airspace to provide
additional fuel, increasing fighter range and endurance. Air
Air Defenses. The sophistication of air defenses varies
planners consider these strategically important aircraft
widely around the world, from individual, poorly
relatively defenseless. This means they would require
coordinated anti-aircraft guns to integrated air defense
networks coupled with high-performance surface-to-air
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What Is a No-Fly Zone (NFZ)?
missile systems and modern fighter aircraft. The
the Gulf War. That understanding may also be informed by
characteristics of a given air defense system will indicate
current intelligence based on input from a variety of
whether establishing an NFZ requires that the defenses be
possible platforms and assets. If the adversary uses a large
destroyed, suppressed (by jamming, network attack, or
fixed-wing transport fleet to move troops around the
other means), or merely bypassed. It will also dictate in part
country, or if it has a large concentration of fighter aircraft
the tactics required for the initial suppression of enemy air
near a border with an ally or partner in the region and a
defenses; for example, whether it can best be done by
track record of some hostility with that state, these factors
manned aircraft, standoff weapons such as cruise missiles,
may shape the priorities of the NFZ operations. Adversary
and/or unmanned aircraft.
artillery could also affect military planning. Artillery shells
and rockets fly at relatively high altitudes, requiring aircraft
Adversary Aircraft. The size of the adversary air
to either avoid certain areas to prevent an accidental impact,
component to be suppressed—not only the number of
or to fly at higher altitudes and therefore potentially
aircraft, but also bases—also informs the capabilities that
minimize their effective presence.
the U.S. and partner forces would have to bring to bear. The
quality of the air assets—particularly the quality and
Rules of Engagement. Those imposing an NFZ operation
training of fighter forces, and the effectiveness of their
may choose to limit it formally in scope, in the area of
command and control system—affects the defensive assets
operation, in allowable weapons and tactics, or in other
that would have to be included in the NFZ force package, as
ways, in order to avoid civilian casualties or other losses, to
well as the balance of efforts dedicated to offensive action
incentivize defections by adversary forces, to restrict
against the enemy, and to defensive action to enhance the
actions likely to alienate partners, or for other strategic
survival of “friendly” forces.
considerations.
Geography. The geographical boundaries of an NFZ help
Potential Considerations for Congress
define both the relevant assets and the level of SEAD
Historically, NFZs have required supplemental funding.
required. For example, an NFZ focused on coastal areas
Adjusting for inflation, on average from FY1993 through
could allow “friendly” naval air assets to engage more
FY2003 the Department of Defense (DOD) requested $1.1
readily, and may not require the same level of SEAD as an
billion in FY2022 dollars for both Northern Watch and
NFZ that requires tactical aircraft (and especially
Southern Watch. Similarly, in FY2001, DOD requested
supporting assets like tankers) to penetrate deeply into the
approximately $2.8 billion supplemental funding in
defended airspace. Similarly, an NFZ that denies flight only
inflation adjusted dollars for operations over the Balkans.
over major urban areas, for example, reduces the resource
requirements for the NFZ compared to denial of air activity
In addition, NFZs reportedly have expended large amounts
over a whole country, as in Bosnia and Herzegovina, or
of munitions. According to defense analysts Mike Pietrucha
major areas of a country, as in northern and southern Iraq.
and Mike Benitez, U.S. and coalition aircraft expended 743
The proximity of allied and partner states can affect the
high-speed anti-radiation missiles and nearly 1,500 towed
availability of basing for land-based tactical aircraft and
decoys to eliminate the threat of Serbian air defenses during
UAVs—the negotiation of new agreements regarding
Operation Allied Force. In FY2022, DOD requested
basing, access, and overflight, if required, can take time.
funding for 54 Advanced Anti-Radiation Guided Missiles,
The proximity of oceans, in turn, can provide navigable
the successor to the high-speed anti-radiation missile.
waters for carrier-based aircraft and/or cruise missile-
Assuming a similar missile procurement rate, replacing
equipped ships.
these expended munitions would take nearly 14 years.
Availability of Assets. Plans for resourcing an NFZ may be
CRS Products
shaped by concurrent or potential competing demands, in
particular for “high-demand, low-density” assets such as
CRS In Focus IF10546, Defense Primer: United States Airpower,
intelligence, surveillance, and reconnaissance (ISR). The
by Jeremiah Gertler
participation of allies and partners can reduce the demands
CRS Report R45996, Precision-Guided Munitions: Background
on U.S. forces for some capabilities. Depending on the
and Issues for Congress, by John R. Hoehn
scenario, though, the capabilities of partners in areas such
CRS Report R46463, U.S. Army Short-Range Air Defense Force
as surveillance, and command and control, may not be
Structure and Selected Programs: Background and Issues for
sufficiently robust to provide equivalent effectiveness.
Congress, by Andrew Feickert
Adversary Strategy. Strategists generally argue that an
understanding of the adversary’s strategy and likely tactics
should help inform the operational-level objectives of an
NFZ operation. That understanding may be based in part on
John R. Hoehn, Analyst in Military Capabilities and
precedent; for example, the Iraqi government’s use of
Programs
chemical weapons against its own northern Kurdish
Andrew Feickert, Specialist in Military Ground Forces
population in 1988, and its use of fixed-wing and rotary-
IF12059
wing aircraft to strafe the population in southern Iraq after
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What Is a No-Fly Zone (NFZ)?
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