A war in Greenland doesn't even make logistical sense. You would be fighting the only people that actually know how to deal with the cold.

All anyone would need to do is blow up the generators and it would be war over, because as far as I know the US military has not trained it's soldiers and how to survive having all their blood frozen. They were expecting the next major conflict to be in the middle East, not inside the Arctic circle.

But who will help the USA...

They turned a blind eye in Gaza. That was the death of any pretext of international law which still existed after the """War on Terror""".

Colombia is more vulnerable but it hasn't developed a lobby like Venezuela and Cuba have.

Sheinbaum in Mexico and Lula in Brazil are later in the itinerary but they're going to be more difficult. Especially Brazil now that Bolsonaro is in jail.

The rainforests would be toxic wastelands within a few years.