a) FDR was one of the people responsible for creating the United Nations from the defunct "League of Nations" that the US had helped destroy in the 1930's. There were FIVE permanent members on the UN Security Council -- Britain, France, The US, The Soviet Union (not Russia) plus Nationalist China. Currently it is the same although Nationalist China (Taiwan) has been replaced by mainland China.
b) The US and Britain along with the Soviet Union were the main world leading countries but ONLY the US took up the role of arrogantly becoming the "World Policeman".
c) The internal politics of Iran, and other countries, are just that, INTERNAL. When national affairs start to affect other countries, it should be the UN that becomes involved, NOT the US.
d) The US constantly violates international laws, treaties, agreements and the UN Charter. They are able to do so because of their military and economic strengths blackmailing other countries.