I am waiting for someone to identify the US constitutional provision which empowers the US Congress to annex another country/State. I find no power to annex enumerated in the US Constitution [https://en.wikipedia.org/wiki/Enumerated_powers]. International law recognizes annexation, in certain instances, via a treaty, but there is no annexation treaty. Non-treaty based annexation of another State is not an enumerated power nor does it seem to be a "necessary and proper" power. Congress doesn't possess the authority to annex.. "This government is acknowledged by all, to be one of enumerated powers. The principle, that it can exercise only the powers granted to it, would seem too apparent, to have required to be enforced by all those arguments, which its enlightened friends, while it was depending before the people, found it necessary to urge; that principle is now universally admitted. [https://en.wikipedia.org/wiki/Enumerated_powers]. Cheers.