They kinda do, via sattelite pings, radar, etc. Whether they have radar coverage is another matter. I'm confident they have coverage all along the US coast and

They kinda do, via sattelite pings, radar, etc. Whether they have radar coverage is another matter. I'm confident they have coverage all along the US coast and military bases, but other areas are temporary, like the AWACS flying over UN territory looking into Russia and Ukraine to provide the Ukrainians with intel (one from the French air force flying over Romania: https://apnews.com/article/ukraine-russia-surveillance-defense-war-65b93d45f67204c9db7a07330e722097 https://apnews.com/article/ukraine-russia-surveillance-defen... and another over Poland: https://www.cbc.ca/news/world/flying-with-nato-awacs-1.6619471 https://www.cbc.ca/news/world/flying-with-nato-awacs-1.66194...)