Article 2(4) of the United Nations Charter, to which all Coalition countries are signatories and for which its ratification by the US makes it the "law of the land", prohibits the 'threat or use of force against the territorial integrity or political independence of any state' except in circumstances where a competent organ of the UN (e.g. the Security Council) has authorized it, or where it is in self-defense under article 51 of the Charter. Although the United Nations Security Council (UNSC) did not authorize the US-led military campaign, some argued it was a legitimate form of self-defense under the UN Charter.