40 countries, comprising 85% of the world's population, and a combined GDP for every nation but China somewhere between that of either Connecticut or Wyoming. In a good year.

Why does anyone pay any attention to those shithole countries for anything?

Oh, and in addition to the tarriffs you suggested, a ban on any further US immigration from those countries, until further notice. No friends, no relatives, nobody. Anybody here from them on a green card has to go back as well.

All US aid thenceward suspended indefinitely, and recall all development loans as well.

If you like your Turd World shithole, you can keep your Turd World shithole. Actions have consequences. Enjoy the dung heap.