Can we annex Mexico?
The problem with annexing it is that you have to do way to many purges for it to be economically viable in the short term.
Besides those purges are not the American way...yet. We have to goad them into a fight. Not hard. Trying to interfere in domestic affairs is usually a very major deal in the UN so by law we could. Though like Isreal we are always the Great Satan no matter what we do.
Then again with the influx of resources we won’t need as much trade with those countries we might lose favor with.