A top U.S. general said Thursday that the Pentagon has informed Russia of where U.S. Special Operations forces are operating in Syria.

Air Force Lt. Gen. Charles Q. Brown, commander of U.S. Air Force Central Command, told reporters that the United States has outlined to the Russians where the U.S. forces are operating in “not specific areas, but firmly broad areas” to ensure the troops’ safety.

Pentagon press secretary Peter Cook would not go into specifics regarding the size of those areas detailed by Brown. Cook said the “highest levels” of leadership within the Pentagon have discussed the Special Operations forces’ locations with the Russians but refrained from saying when those discussions took place. Brown, however, said that the Russians have been made aware of the Special Operations forces’ presence within Syria around the same time the Pentagon announced their deployment in December.

In October, roughly a month after Russia started airstrikes in Syria, the Pentagon and the Russian Ministry of Defense established a memorandum of understanding that outlined “specific safety protocols for air crews to follow” so that Russian and U.S. aircraft could avoid one another in the rapidly crowding skies over Syria.

According to Cook, at the time of the memorandum’s announcement, the document specifically did not “establish zones of cooperation, intelligence sharing or any sharing of target information in Syria.”

On Thursday, Cook explained that giving the Special Operations forces’ location to the Russians was the only instance in which the United States has gone outside the framework of the original memorandum. He said it was done to provide additional safety to U.S. forces operating on the ground.

Though Russian airstrikes have been largely directed toward supporting Syrian President Bashar al-Assad’s ground forces, some airstrikes have hit the Islamic State in areas where U.S. aircraft are operating. It is unclear how close Russian aircraft have flown to U.S. ground forces, if they have at all.

The White House authorized the deployment of approximately 50 Special Operations troops to northern Syria late last year to help assess and potentially train U.S.-backed local forces fighting the Islamic State. The location of the Special Operations troops has been kept largely secret for security purposes, and details of their mission have not been disclosed.