Could be just a panic move, US has been making terrible decisions for a while now. This would be par for the course. They’re seeing that Syria is back in the Arab league, and have backing from Russia and Iran. With Saudis now restoring relations with Syria, US occupation forces are in a really precarious position. This could be some sort of a bluff. Realistically though, 2.5k troops aren’t going to make any difference for them there. It’s just the throes of a dying empire.