Order Code RS21311
September 18, 2002
CRS Report for Congress
Received through the CRS Web
U.S. Use of Preemptive Military Force
Richard F. Grimmett
Specialist in National Defense
Foreign Affairs, Defense, and Trade Division
Summary
This report reviews the historical record regarding the uses of U.S. military force
in a “preemptive” manner, an issue that has emerged due to the possible use of U.S.
military force against Iraq. It examines and comments on military actions taken by the
United States that could be reasonably interpreted as “preemptive” in nature. For
purposes of this analysis we consider a “preemptive” use of military force to be the
taking of military action by the United States against another nation so as to prevent or
mitigate a presumed military attack or use of force by that nation against the United
States. This review includes all noteworthy uses of military force by the United States
since the establishment of the Republic. A listing of such instances can be found in
CRS Report RL30172, Instances of Use of United States Armed Forces Abroad, 1798-
2001. For an analysis of international law and preemptive force see CRS Report
RS21314, International Law and the Preemptive Use of Force Against Iraq.
Background
In recent months the question of the possible use of “preemptive” military force by
the United States to defend its security has been raised by President Bush and members
of his Administration, including possible use of such force against Iraq.1 This analysis
reviews the historical record regarding the uses of U.S. military force in a “preemptive”
manner. It examines and comments on military actions taken by the United States that
could be reasonably interpreted as “preemptive” in nature. For purposes of this analysis
we consider a “preemptive” use of military force to be the taking of military action by the
United States against another nation so as to prevent or mitigate a presumed military
attack or use of force by that nation against the United States. The discussion below is
based upon our review of all noteworthy uses of military force by the United States since
establishment of the Republic.
Historical overview. The historical record indicates that the United States has
never, to date, engaged in a “preemptive” military attack against another nation. Nor has
1 See speeches of President George W. Bush at West Point on June 1, 2002 at
[http://www.whitehouse.gov/news/releases/2002/06/20020601-3.html]; and the President’s United Nations.
speech of September 12, 2002 at [http://www.whitehouse.gov/news/releases/2002/09/20020912-1.html];
Washington Post, June 2, 2002, p. A1; Washington Post, September 13, 2002, p.A1.
Congressional Research Service ˜ The Library of Congress

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the United States ever attacked another nation militarily prior to its first having been
attacked or prior to U.S. citizens or interests first having been attacked, with the singular
exception of the Spanish-American War. The Spanish-American War is unique in that
the principal goal of United States military action was to compel Spain to grant Cuba its
political independence. An act of Congress passed just prior to the U.S. declaration of war
against Spain explicitly declared Cuba to be independent of Spain, demanded that Spain
withdraw its military forces from the island, and authorized the President to use U.S.
military force to achieve these ends.2 Spain rejected these demands, and an exchange of
declarations of war by both countries soon followed.3 Various instances of the use of
force are discussed below that could, using a less stringent definition, be argued by some
as historic examples of “preemption by the United States. The final case, the Cuban
Missile crisis of 1962, represents a threat situation which some may argue had elements
more parallel to those presented by Iraq today–but it was resolved without a “preemptive”
military attack by the United States.
The circumstances surrounding the origins of the Mexican War are somewhat
controversial in nature–but the term “preemptive” attack by the United States does not
apply to this conflict. During, and immediately following the First World War, the United
States, as part of allied military operations, sent military forces into parts of Russia to
protect its interests, and to render limited aid to anti-Bolshevik forces during the Russian
civil war. In major military actions since the Second World War, the President has either
obtained Congressional authorization for use of military force against other nations, in
advance of using it, or has directed military actions abroad on his own initiative in support
of multinational operations such as those of the United Nations or of mutual security
arrangements like the North Atlantic Treaty Organization (NATO). Examples of these
actions include participation in the Korean War, the 1990-1991 Persian Gulf War, and the
Bosnian and Kosovo operations in the 1990s. Yet in all of these varied instances of the
use of military force by the United States, such military action was a “response,” after the
fact, and was not “preemptive” in nature.
Central American and Caribbean interventions. This is not to say that the
United States has not used its military to intervene in other nations in support of its
foreign policy interests. However, U.S. military interventions, particularly a number of
unilateral uses of force in the Central America and Caribbean areas throughout the 20th
century were not “preemptive” in nature. What led the United States to intervene
militarily in nations in these areas was not the view that the individual nations were likely
to attack the United States militarily. Rather, these U.S. military interventions were
grounded in the view that they would support the Monroe Doctrine, which opposed
interference in the Western hemisphere by outside nations. U.S. policy was driven by the
belief that if stable governments existed in Caribbean states and Central America, then
2 Joint Resolution of April 20, 1898, [Res. 24] 30 Stat. 738.
3 There was no direct military attack by Spain against the United States prior to the exchange of declarations
of war by the nations, and initiation of hostilities by the United States in 1898. See Declarations of War and
Authorizations for the Use of Military Force: Background and Legal Implications. CRS Report RL31133,
by David M. Ackerman and Richard F. Grimmett. A notable event, the sinking of the U.S.S. Maine in
Havana harbor, provided an additional argument for war against Spain for those advocating it in the United
States. The actual cause of the sinking of the U.S.S. Maine in Havana harbor, even today, has not been
definitively established. More recent scholarship argues that it was most likely not due to an external attack
on the ship, such as the use of a mine by an outside party, but due to an internal explosion.

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it was less likely that foreign countries would attempt to protect their nationals or their
economic interests through their use of military force against one or more of these nations.
Consequently, the United States, in the early part of the 20th century, established
through treaties with the Dominican Republic (in 1907)4 and with Haiti (in 1915)5, the
right for the United States to collect and disperse customs income received by these
nations, as well as the right to protect the Receiver General of customs and his assistants
in the performance of his duties. This effectively created U.S. protectorates for these
countries until these arrangements were terminated during the Administration of President
Franklin D. Roosevelt. Intermittent domestic insurrections against the national
governments in both countries led the U.S. to utilize American military forces to restore
order in Haiti from 1915-1934 and in the Dominican Republic from 1916-1924. But the
purpose of these interventions, buttressed by the treaties with the United States, was to
help maintain or restore political stability, and thus eliminate the potential for foreign
military intervention in contravention of the principles of the Monroe Doctrine.
Similar concerns about foreign intervention in a politically unstable Nicaragua led
the United States in 1912 to accept the request of its then President Adolfo Diaz to
intervene militarily to restore political order there. Through the Bryan-Chamorro treaty
with Nicaragua in 1914, the United States obtained the right to protect the Panama Canal,
and its proprietary rights to any future canal through Nicaragua as well as islands leased
from Nicaragua for use as military installations. This treaty also granted to the United
States the right to take any measure needed to carry out the treaty’s purposes.6 This treaty
had the effect of making Nicaragua a quasi-protectorate of the United States. Since
political turmoil in the country might threaten the Panama Canal or U.S. proprietary rights
to build another canal, the U.S. employed that rationale to justify the intervention and
long-term presence of American military forces in Nicaragua to maintain political
stability in the country. U.S. military forces were permanently withdrawn from Nicaragua
in 1933. Apart from the above cases, U.S. military interventions in the Dominican
Republic in 1965, Grenada in 1983, and in Panama in 1989 were based upon concerns
that U.S. citizens or other U.S. interests were being harmed by the political instability in
these countries at the time U.S. intervention occurred. While U.S. military interventions
in Central America and Caribbean nations were controversial, after reviewing the context
in which they occurred, it is fair to say that none of them involved the use of “preemptive”
military force by the United States.7
Covert action. Although the use of “preemptive”force by the United States is
generally associated with the overt use of U.S. military forces, it is important to note that
4 7 UST 196.
5 8 UST 660.
6 10 UST 379.
7 For an excellent background discussion of U.S. policy toward the Caribbean and Central American
nations during the first half of the 20th century see: Samuel Flagg Bemis, A Diplomatic History of the United
States. New York. Holt, Rinehart and Winston, Inc. 1965, pp. 519-538. For a detailed historical study that
provides valuable insights and commentary on U.S. actions taken toward Caribbean and Central American
countries see chapters 9, 11, and 12 in Samuel Flagg Bemis, The Latin American Policy of the United
States. New York. Harcourt, Brace & World , 1943. [reprinted in paperback in New York, by W.W. Norton
& Company, Inc., 1967].

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the United States has also utilized “covert action” by U.S. government personnel in efforts
to influence political and military outcomes in other nations. The public record indicates
that the United States has used this form of intervention to prevent some groups or
political figures from gaining or maintaining political power to the detriment of U.S.
interests and those of friendly nations. For example, the use of “covert action” was
widely reported to have been successfully employed to effect changes in the governments
of Iran in 1953, and in Guatemala in 1954. Its use failed in the case of Cuba in 1961. The
general approach in the use of a “covert action” is reportedly to support local political and
military/paramilitary forces in gaining or maintaining political control in a nation, so that
U.S. or its allies interests will not be threatened. None of these activities has reportedly
involved significant numbers of U.S. military forces because by their very nature “covert
actions” are efforts to advance an outcome without drawing direct attention to the United
States in the process of doing so.8 Such previous clandestine operations by U.S. personnel
could arguably have constituted efforts at “preemptive” action to forestall unwanted
political or military developments in other nations. But given their presumptive limited
scale compared to those of major conventional military operations, it seems more
appropriate to view U.S.“covert actions” as adjuncts to more extensive U.S. military
actions. As such, prior U.S. “covert actions” do not appear to be true case examples of
the use of “preemptive” military force by the United States.
Cuban missile crisis of 1962. The one significant, well documented, case of
note, where “preemptive” military action was seriously contemplated by the United
States, but ultimately not used, was the Cuban missile crisis of October 1962. When the
United States learned from spy-plane photographs that the Soviet Union was secretly
introducing nuclear-capable, intermediate-range ballistic missiles into Cuba, missiles that
could threaten a large portion of the Eastern United States, President John F. Kennedy had
to determine if the prudent course of action was to use U.S. military air strikes in an effort
to destroy the missile sites before they became operational, and before the Soviets or the
Cubans became aware that the U.S. knew they were being installed. While the military
“preemption” option was considered, after extensive debate among his advisors on the
implications of such an action, President Kennedy undertook a measured but firm
approach to the crisis that utilized a U.S. military “quarantine” of the island of Cuba to
prevent further shipments from the Soviet Union of military supplies and material for the
missile sites, while a diplomatic solution was aggressively pursued. This approach was
successful, and the crisis was peacefully resolved.9
8 Section 503(e) of the National Security Act of 1947, as amended, defines covert action as “An activity or
activities of the United States Government to influence political, economic or military conditions abroad,
where it is intended that the role of the United States Government will not be apparent or acknowledged
publicly.”
9 For detailed background regarding the issues surrounding the possible use of “preemptive” military force
against the Soviet missile sites being established in Cuba, and the deliberative process engaged in by
President Kennedy and his key advisors, see the published transcripts of tape recordings made during their
White House meetings in The Kennedy Tapes: Inside the White House during the Cuban Missile Crisis.
Ernest R. May and Philip D. Zelikow (eds.). Cambridge, Massachusetts. Harvard University Press, 1997.

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