AL-TANF, Syria (AP) — The top U.S. commander for the Middle East has flown into a key outpost in Southern Syria where troops are fighting remnants of the Islamic State and trying to block Iranian-backed forces from gaining a foothold.

Army Gen. Joseph Votel was making an unannounced visit to the al-Tanf garrison near the borders of Iraq and Jordan. The garrison supports 200-300 U.S. and coalition troops training Syrian opposition forces to fight the Islamic State.

Votel says the coalition has "largely eliminated" the insurgent group's ability to occupy territory in Syria. But he says the troop presence remains vital to counter growing Iranian activity in the area.

Votel visited the area Monday with journalists from The Associated Press and two other organizations.