Conquest fell out of fashion with the bomb; it's all proxy wars, psyops, and deniable covert/cyber attacks now. Slamming the door on H-1B’s (while it might be nice for my own income) weakens American companies and sends world talent elsewhere, like China. Who's only too happy to fund infrastructure in Greenland/Africa/Europe to extend soft power across the globe while siezing harder power closer to home (Hong Kong, South Sea expansionism, etc). Sitting out the game isn't an option, and going at it alone ain't much better.