U.S. Use of Preemptive Military Force

CRS Report for Congress
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 emerged during public debates prior to the use
of U.S. military force against Iraq in 2003. 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 a preemptive use of military force is considered to
be the taking of military action by the United States against another nation so as to
prevent or mitigate a presumed imminent military attack or use of force by that nation
against the United States. The deployment of U.S. military forces in support of U.S.
foreign policy, without their engaging in combat, is not deemed to be a preemptive use
of military force. 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 RL32170, Instances of Use of United States Armed Forces
Abroad, 1798-2003. For an analysis of international law and preemptive force see CRS
Report RS21314, International Law and the Preemptive Use of Force Against Iraq. This
report will be updated if significant events warrant.
Background
During the summer and fall of 2002, the question of the possible use of “preemptive”
military force by the United States to defend its security was raised by President Bush and
members of his Administration, including possible use of such force against Iraq. In mid-
September 2002, the Bush Administration published The National Security Strategy of
the United States which explicitly states that the United States is prepared to use
preemptive military force to prevent U.S. enemies from using weapons of mass
destruction (WMD) against it or its friends or allies¹ The following analysis reviews the

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 UN on 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. The National Security
Strategy of the United States of America is found at [http://www.whitehouse.gov/nsc/nss.html].
Also see speeches of Vice President Dick Cheney before the National Association of Home
(continued...)
Congressional Research Service ˜ The Library of Congress

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 a preemptive
use of military force is considered 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 deployment of U.S. military forces in
support of U.S. foreign policy, without their engaging in combat, is not deemed to be a
preemptive use of military force. Preemptive use of military force is also deemed to be
an action addressed at a specific and imminent military threat, requiring timely action²
By contrast, a “preventive war” would be a significant use of military force against
a nation as a “preventive” action, to forestall a presumed military threat from that nation
at some point in the future, whether months or years. Such an action would be outside the
traditional parameters of the concept of preemptive use of military force. It would be a
significant expansion of the customary understanding of the elements that define such an
action. However, such an expansive view of military preemption is contained in the Bush
Administration’s September 2002 U.S. National Strategy document, and in related public
policy statements by senior Bush Administration officials. Thus, various instances of the
use of force that are examined herein could, using a less stringent definition, be argued
by some as examples of preemption by 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, as traditionally defined, against
another nation. And only once has the United States ever unilaterally attacked another
nation militarily prior to its first having been attacked or prior to U.S. citizens or interests
first having been attacked. That instance was the Spanish-American War of 1898. In that
military conflict, the principal goal of United States military action was to compel Spain

¹ (...continued)
Builders on June 6, 2002 found at [http://www.whitehouse.gov/vicepresident/news-
speeches/speeches/vp20020606.html]., where he stated: “...we also realize that wars are not won
on the defensive. We must take the battle to the enemy-and, where necessary, preempt grave
threats to our country before they materialize.” And the Vice President’s speech before the
Veterans of Foreign Wars National Convention on August 26, 2002 found at
[http://www.whitehouse.gov/news/releases/20020826.html] where he noted that “...containment
is not possible when dictators obtain weapons of mass destruction, and are prepared to share them
with terrorists who intend to inflict catastrophic casualties on the United States.”
² It is important to note here the historic and traditional view of the United States government on
what constitutes the legitimate use of preemptive military force in accordance with international
law. This view was best articulated by then Secretary of State, Daniel Webster, in 1842, in
diplomatic correspondence with the British Government. Webster stated that it was an act of self-
defense permitting an intrusion into the territory of another state only in those “cases in which
the necessity of that self-defense is instant, overwhelming, and leaving no choice of means and
no moment for deliberation.” See letter from Secretary of State Daniel Webster to Lord
Ashburton of August 6, 1842, reprinted in Moore, John Bassett, A Digest of International Law,
Vol. II (1906), p. 412. For a detailed discussion of international law and preemptive use of
military force see CRS Report RS21314, International Law and the Preemptive Use of Force
Against Iraq, by David M. Ackerman.

to grant Cuba its political independence. An act of Congress, passed in April 1898, 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, if necessary.³
Spain rejected these demands, and an exchange of declarations of war by both countries
soon followed thereafter.⁴ Although U.S. military actions against Spain were based on
special U.S. foreign policy considerations, they occurred after war was formally declared,
and cannot be fairly characterized as preemptive in nature. During the Cuban Missile
crisis of 1962, preemptive use of military force to destroy Soviet missiles that had been
introduced into Cuba was very seriously considered in the early days of the crisis, but the
matter was ultimately resolved diplomatically. Although the United States did not use
military force “preemptively,” it did deploy military forces as an adjunct to its diplomacy,
while reserving its right to take additional military actions as it deemed appropriate.
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. The use of military force against Iraq in
2003, while controversial within the international community, was justified by the United
States, the United Kingdom and others, as an action necessary to enforce existing U.N.
Security Council resolutions that mandated Iraqi disarmament. 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, as traditionally defined.
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 20^th
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

³ Joint Resolution of April 20, 1898, [Res. 24] 30 Stat. 738.
⁴ 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: Historical 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.

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 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 20^th century, established
through treaties with the Dominican Republic (in 1907)⁵ and with Haiti (in 1915)⁶, 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.⁷ 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.⁸

⁵ 7 UST 196.
⁶ 8 UST 660.
⁷ 10 UST 379.
⁸ For an excellent background discussion of U.S. policy toward the Caribbean and Central
American nations during the first half of the 20^th 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
(continued...)

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
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 United⁹
States in the process of doing so. 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, and also that they were not
used to preempt an imminent military attack on the United States, it seems more
appropriate to view U.S.“covert actions” as adjuncts to more extensive U.S. military
actions in support of U.S. foreign policy. As such, these 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 seriously 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. naval “quarantine” of the island of Cuba to
prevent receipt of additional missile shipments from the Soviet Union as well as military
supplies and material for the existing missile sites, while a diplomatic solution was
aggressively pursued. At the same time, the U.S. reserved the right to employ the full

⁸ (...continued)
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].
⁹ 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.”

range of military actions should diplomacy fail. This approach was successful, and the
crisis was peacefully resolved.¹⁰
Iraq War of 2003. In the case of the Iraq War of 2003, the United States has used
significant military force against that nation even though the U.S. was not attacked first
by Iraq. Various public speeches made by the Bush Administration during the summer
and fall of 2003 noted that the United States was prepared to engage in “preemptive”
military action against unfriendly nations in advance of their becoming an “imminent”
military threat to the U.S. In September 2002, the Bush Administration published The
National Security Strategy of the United States of America which explicitly states that the
United States is prepared to use preemptive military force to prevent enemies of the
United States from using weapons of mass destruction (WMD) against it or its allies and
friends. The timing of the release of this strategy document, together with statements of
senior Bush Administration officials regarding the potential threat to the U.S. that Iraq’s
WMD program posed, led to speculation that Iraq could be the first case where the
expansive approach to use of preemptive military force would be applied. Subsequently,
the Bush Administration sought and obtained passage of U.N. Security Council
Resolution 1441 on November 8, 2002, which, among other things, noted that Iraq was
still in material breach of its obligations under prior U.N. Security Council resolutions to
destroy and not to seek to obtain various proscribed weapons and capabilities. UNSCR
1441 further noted that “serious consequences” would result from failure of Iraq to
comply unconditionally with its obligations contained in the U.N. Resolutions.¹¹
When President Bush launched U.S. military action against Iraq on March 19, 2003,
he stated he was doing so, with coalition forces, to enforce existing UN Security Council
Resolutions that had been violated by Iraq since the Gulf War of 1990-1991—Security
Council Resolutions that expressly contemplated the use of force should Iraq not comply
with them—and also to protect the security of the U.S. In a March 19, 2003 report to
Congress on the issue, President Bush noted his conclusion and determination that further
diplomatic efforts to enforce the U.N. imposed obligation that Iraq destroy its WMD
would not succeed, thus requiring the use of military force to achieve Iraqi disarmament.
The President did not explicitly characterize his military action as an implementation of
the expansive concept of preemptive use of military force against rogue states with WMD
contained in his National Security Strategy document of September 2002.¹² However, as
U.S. military action was justified to protect the security of the United States from a
prospective, but not imminent threat of military action by Iraq, it could be argued that,
measured against the traditional concept of preemptive use of military force, this was an
act of “preventive war”by the United States.

¹⁰ 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.
¹¹ [http://ods-dds-ny.un.org/doc/UNDOC/GEN/N02/682/26/PDF/N0268226.pdf?OpenElement]
¹² [http://www.whitehouse.gov/news/releases/2003/03/20030321-5.html]; House Document 50,

108th Congress, 1^st session.