Trump made no mention of the troops that were staying behind.

"Our soldiers have left and are leaving Syria for other places, then ... COMING HOME!" he wrote.

Some reports have said the U.S. is deploying tanks. But the military typically refers to units equipped with Bradley fighting vehicles as mechanized forces and to units with Abrams tanks as armored forces. It wasn’t clear from Esper’s remarks how many troops would stay at the oil fields or what types of vehicles will be sent in, but an Army brigade in Kuwait is outfitted with both Bradleys and tanks.

The Wall Street Journal reported Thursday that as many as 500 troops could be staying in Syria.

Under Trump’s original pullout order, most of the 1,000 U.S. forces in Syria were to leave, with a small force to remain at the southern garrison in al-Tanf. The oil field mission represents a partial reversal of that move. The Trump administration’s special representative for Syria, James Jeffrey, suggested this week that the military also plans to keep open an airfield in the country’s northeast as a logistics hub.

Esper this week said the U.S. forces leaving Syria would head into western Iraq. But after Iraqi leaders said those troops can't stay there, Esper said they will be deployed in Iraq only temporarily before coming home.

The defense chief also said Kurdish troops are recapturing ISIS members who escaped from Kurdish-run prisons in the northeast since the start of Turkey’s incursion into Syria.

“The SDF has assured us that all ISIS prisoners are being secured,” he said, referring to the Kurdish-led Syrian Democratic Forces.

