If Xi's underlings were in Mexico City all the time telling the Mexican government and even the cartels (similar to the Ukrainian Ultra-Nationalists/Nazi's like the Azov's) that they're going to support Mexico every step of the way in aggressive provocations and even war with the United States, we'd be invading tomorrow. Particularly if Mexico stated the intended to join BRICS or something similar.
We most certainly would not do that, even under your extremely tortured analogy.
Name a single time that a country on our periphery has aligned themselves with a geo-strategic competitor where the United States has not done at least one of these things: Invaded, attempted invasion, supported insurgencies, prosecuted coups, attempted to prosecute coups, blockaded (that's a military action), assassinations, attempted assassinations, economic sanctions, supported opposition politicians (even if they were the worst people on the planet)
In several cases, we've done, "all the above"