Any objection may be raised at the U.S. military intervention (assuming it will take place), except that it is not fully and legitimately included in the United Nation's Statute (art.42), and explicitly provided for by resolution n.678 of the Security Council.
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Article 42
If the Security Council judges the measures provided for in art.41 to be inadequate or to have proven inadequate, it may undertake any action necessary to maintain or restore peace and international security by means of air, naval or land forces.
Such action can include demonstrations, blocks and other operations carried out by means of air, naval or land forces of the members of the United Nations.