The U.S. military more than doubled the number of troops it has in Syria to fight ISIS prior to the collapse of the Assad regime earlier this month.

Pentagon officials have long said the United States had about 900 troops in the country, the exact total fluctuating frequently due to the ending and beginning of various deployments, though Maj. Gen. Patrick Ryder, the Pentagon’s spokesman, told reporters on Thursday that the tally is actually around 2,000 troops.