The Supreme Court ruled in the Head Money Cases that "treaties" do not have a privileged position over Acts of Congress and can be repealed or modified (for the purposes of U.S. law) by any subsequent Act of Congress, just like with any other regular law. The Supreme Court also ruled in Reid v. Covert that any treaty provision that conflicts with the Constitution are null and void under U.S. law.
What Supreme Court case ruled that a treaty provision that conflicts with the US Constitution is null and void under US law?
Reid v. Covert