Defense Secretary Mark Esper said on Monday that President Donald Trump may leave some U.S. troops in northern Syria to protect the region’s oil fields from coming under Islamic State control, according to The Associated Press.

Trump ordered U.S. armed forces out of the region earlier this month, ahead of Turkey’s planned offensive against the American-allied Kurdish forces. Though he received bipartisan criticism for the move, Trump justified the withdrawal by citing his promise to pull American out of “endless wars.”

His critics warned the decision would greenlight a Turkish invasion and cost Kurdish lives, also accusing the president of abandoning a key American ally in the fight against ISIS.

Esper said the plan is still under discussion and “emphasized that the proposal to leave a small number of troops in eastern Syria was intended to give the president ‘maneuver room’ and wasn't final,” the AP reported.

A White House official told the AP that Senator Lindsey Graham (R-SC) raised the idea of leaving a small number of troops in northern Syria to guard the oilfields, adding that Trump was on board.

On Monday, the president maintained his desire to withdraw all U.S. troops from Syria, but he added that “we need to secure the oil.” Trump also said that Jordan and Israel requested a continued U.S. military presence in another area of Syria.

Read the full report.