The UN Charter is legally binding on all United Nations member states, including all members of NATO, because they have each signed it. Article 2(4) of the UN Charter prohibits the use of force by UN member states to resolve disputes, but with two specific exceptions to this general prohibition:
1. The first exception is set forth in Chapter VII--the UN Security Council has the power to authorize the use of force in order to fulfill its responsibility to maintain international peace and security. In particular, Article 42 states that should the Security Council consider that measures provided for in Article 41 would be inadequate or have proved to be inadequate, it may take such action by air, sea, or land forces as may be necessary to maintain or restore international peace and security. Such action may include demonstrations, blockade, and other operations by air, sea, or land forces of Members of the United Nations.[5]
NATO did not have the backing of the United Nations Security Council to use force in Yugoslavia. Further, NATO did not claim that an armed attack occurred against another state.
UN Secretary-General Kofi Annan was critical of unilateral action by NATO. He argued "under the [UN] Charter the Security Council has primary responsibility for maintaining international peace and security - and this is explicitly acknowledged in the North Atlantic Treaty. Therefore, the Council should be involved in any decision to resort to the use of force."[8][9][10]
On the day the bombing started, Russia called for the UN Security Council to meet to consider "an extremely dangerous situation caused by the unilateral military action of the North Atlantic Treaty Organization (NATO) against the Federal Republic of Yugoslavia". However, a draft resolution, tabled jointly by Russia, Belarus and India, to demand "an immediate cessation of the use of force against the Federal Republic of Yugoslavia" was defeated.
Aside from the above-discussed issue of the legal justifiability of launching the war against Yugoslavia, the NATO bombing campaign has been criticized for exceeding the limits of lawful wartime conduct under international humanitarian law, such as the Geneva Conventions.[citation needed]
Noam Chomsky was also highly critical of the NATO campaign and its aerial bombing in particular, where public utilities were bombed in addition to military targets.[28][29] Chomsky argued that the main objective of the NATO intervention was to integrate FR Yugoslavia into the Western neo-liberal social and economic system, since it was the only country in the region which still defied the Western hegemony prior to 1999.[30] He described bombing of the Radio Television of Serbia as an act of terrorism.[31]
https://en.wikipedia.org/wiki/Legiti..._of_Yugoslavia