Are you saying that the President of the U.S. along with the Consent of the Senate, can dissolve the states by making a treaty with a nation who doesn’t like our form of government? Or can impose a form of government which is not a republic? Because that is what you are implying. A treaty is a law. A law can be repealed by the legislature and the President by using another law. Only the states can modify the provisions of the Constitution. And it takes a lot of them.(In reality, 5 idiot members of the Supreme Court can overturn the Constitution, because we let them.)