Ok but how would the US react if Mexico wanted nukes from Russia?

The US couped Ukraine's government, installed a puppet regime, continuously built up a military presence right next to Russia's least defensible point (going so far as to have massive wargames in Ukraine), and violated all of the agreements that were meant to deescalate the situation. The alliance in question has only ever been used to invade and demolish countries that dare not kiss the burger reich's ring despite that alliance ostensibly being for defense against foreign aggression.