The U.S.-led invasion of Iraq violates the basic rules of the United Nations Charter requiring countries to exhaust all peaceful means of maintaining global security before taking military action, and permitting the use of force in self-defense only in response to actual or imminent attack, two U.S. legal groups said Thursday.

The U.N. Security Council's refusal to approve a resolution proposed by the United States, Britain and Spain clarified that the weapons inspection process initiated by Security Council Resolution 1441 last November should have been permitted to continue before military action could be authorized, added The Lawyers' Committee on Nuclear Policy (LCNP) and the Western States Legal Foundation (WSLF).

The two groups, the U.S. affiliates of the International Association of Lawyers Against Nuclear Arms (IALANA), supported an open letter signed by 31 Canadian international law professors released Wednesday that called a U.S. attack against Iraq "a fundamental breach of international law (that) would seriously threaten the integrity of the international legal order that has been in place since the end of the Second World War."