Any country that wants to continue existing. Right now, the majority of Africa for example survives solely based on food, money and other aid that we send them. When that gravy train stops, the continent will burn. They can't farm worth a fuck, they can't maintain their own technology and they don't produce any of the literally tons of medicine they consume that they get from us.

And it will stop. Whether it stops due to a civil war on our part, or simply from lack of resources.

Following this, they'll try to invade Europe once they realize that they can't feed themselves. So if the Europeans want to survive, they will have to institute some fairly harsh new laws, and fast.