As an American I think that would all be reasonable…if the official US position was that Mexico has no right to exist, the Mexican people should be forcibly integrated into our society as 2nd class citizens, and the US Army was in the process of a “peacekeeping operation” in Mexico to carry all this out.
For all our flaws, we respect the borders of our neighbors and don’t have irridentist aspirations that belong in the 19th century. Russia is the aggressor here, and they have demonstrated that they have little interest in global peace or human rights, only increasing their sphere of influence.
Continually rolling over for thugs because it’s what avoids nuclear conflict will only lead to a global order based on thuggery, and it likely won’t even avoid nuclear conflict in the end.