Annex Canada and Mexico

So resource depletion and overpopulation will see the end of liberal democracy and a return to fascist/socialist authoritarian regimes conducting wars of aggressive territorial expansionism. We need to get ahead of the curve for the greater good and we have the best advantage now while the element of suprise still exists and resources are plentiful, they don't have nukes and UK, France, Russia and China secretly wouldn't start a nuclear war over this even though they might threaten to. The only problem would be the insurgency after the conquest which is difficult to defeat for 2 reasons.

1: They are supplied by organized criminals or foreign powers.
We can solve this problem with a naval blockade and a wall.

2: We are afraid to kill the civilians they hide among.
Ghengis Khan never had this problem, we should follow in his example.

Thoughts? Suggestions?

Annexing Canada and Mexico is counterproductive. There should be incentives for people to have less children until we're able to colonize other planets.