Ofc you could argue that genocide could invalidate that contract, though much like the outright war crimes happening in Ukraine, you would have to prove that, to a governing body (and again, doesn’t Israel have a veto power there?)
The United States is the global hegemon. We are not bound by any agreement. And, inevitably, our lawyers can find ways for us to act however we want in such a way that it does not technically violate any agreement we are a party to. No one can bind us against our will.
And no, Israel does not have “veto power” before any international body. Certainly not at the UN or WTO