So a treaty, made by the President and duly ratified by the Senate, is part of the supreme law of the land, under the terms of the United States Constitution itself.
So under the U.S. Constitution, the Charter of the United Nations is part of the supreme law of the United States. How can a soldier refuse to participate in U.N. activities, when ordered by his lawful superior? The constitutional process has been followed to ensure that U.S. participation in U.N. activities is fully constitutional. A soldier who refuses to participate in these circumstances would be acting contrary to the Constitution.