US airstrike kills ISIS leader in Syria: Officials

The U.S. military killed a top Islamic State leader and another member in an airstrike conducted in Syria on Thursday, U.S. Central Command said.

The strike targeted Abu Yusif, also known as Mahmud, in the Dayr az Zawr Province, an area formerly controlled by the Syrian regime and Russians, CENTCOM said.

He and an unidentified ISIS member were killed in the strike, according to CENTCOM.

"ISIS has the intent to break out of detention the over 8,000 ISIS operatives currently being held in facilities in Syria. We will aggressively target these leaders and operatives, including those trying to conduct operations external to Syria," Gen. Michael Erik Kurilla, CENTCOM commander, said in a statement.

The airstrike follows the Pentagon revealing Thursday that the U.S. troop presence in Syria is 2,000, up from the 900 previously publicly known to be in Syria. Maj. Gen. Pat Ryder, Pentagon press secretary, said the troops had been in Syria for a while, since before the fall of Bashar Assad's regime earlier this month.

Ryder explained there are 900 "core" troops who are on longer-term deployments in Syria that last between nine and 12 months, but he disclosed that there are an additional 1,100 troops who are considered to be "temporary rotational forces" and are often deployed for between 30 and 90 days to meet additional requirements in that region.