Did you know that the United Nations decides which wars are legal? The United Nations legalizes most wars started by the United States, Britain and France. Sometimes Russia and China demur. Those nations are the five members of the United Nations Security Council, and they have total say and veto power on all wars. If every other member nation of the General Assembly voted against a war, the Security Council could still approve it.
Those five nations are also the world's worst weapons dealers.