RS21314 -- International Law and the Preemptive Use of Force Against Iraq
Updated April 11, 2003

	Preemptive Military Attacks Under Customary International Law

Until recent decades customary international law deemed the right to use force and even to go to war to be an essentialattribute of every state. The U.S. immediately protested this"extraordinary outrage" and demanded an apology and reparations. Although nominally outlawing most uses of force in international relations by individual States, the UN Charter doesrecognize a right of nations to use force for the purpose of self-defense. (14) Although President Kennedy said that thepurpose of the quarantine was "to defend the security of the United States," the U.S. did not rely on the legal conceptofself-defense either as articulated in Article 51 or otherwise as a justification for its actions. Iraq had not attacked the U.S., nor did it appear to pose an imminent threatof attack in traditional military terms.
On March 19, 2003, the United States, aided by Great Britain and Australia,initiated a military invasion of Iraq. Both the U.S. and Great Britain contended that they had sufficient legalauthority touse force against Iraq pursuant to Security Council resolutions adopted in 1990 and 1991. But President Bush alsocontended that, given the "nature and type of threat posed by Iraq," the U.S. had a legal right to use force "in theexercise ofits inherent right of self defense, recognized in Article 51 of the UN Charter." Given that the U.S. had notpreviously beenattacked by Iraq, that contention raised questions about the permissible scope of the preemptive use of force underinternational law. This report examines that issue as it has developed in customary international law and under theUnitedNations Charter. It will be updated as events warrant. (For historical information on the preemptive use of forceby theU.S., see CRS Report RS21311, U.S. Use of Preemptive Military Force.)