The U.S. signed and ratified the Charter of the United Nations which forbids going just anywhere and killing people because that's an aggression.

What's more; the U.S. signed and ratified the North Atlantic Treaty which expressly requires its members to follow the principles of the United Nations.


Veto right or not - the idea that the U.S. could legitimately kill people in foreign countries (instead of going the diplomatic route and asking UN to sanction that safe haven) is incompatible with too much to list here.

Seriously, it's a disrespectful and very arrogant idea. Don't be surprised if even formal allies turn sometime against you if you disrespect treaty obligations like this.