Well, firstly, if you want to believe what the USG is saying about troop levels, that's your prerogative, I guess. How many do we have in Mali, I wonder?
Anyway, it doesn't matter how many US troops we have there, it matters how many US-backed and controlled Kurdish troops are there. Remember, the Kurds are our "allies" in Syria - along with Al Qaeda, of course.
Look at a map of who controls what in Syria. Wherever you see "Kurds" that is USA.
I know that this may come as a surprise to you, John, but the US government has been known to use what we like to call "proxies".
Ukraine is another example of this, BTW. If you think that the current conflict is simply a tussle between Ukraine and Russia, THINK AGAIN.