That ought to do the job; Article VI of the Constitution plainly states that "This Constitution, and the Laws of the United States which shall be made in Pursuance thereof; and all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding."
In other words, if there is a treaty obligation, that trumps all other considerations.
How does the US become party to a treaty, in any case? I'm guessing it has something to do with Congress.
Article II, Section 2 of the Constitution spells this out: "[The President] shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur..."
This seems like a bit of circular reasoning.
How so?