WASHINGTON, Aug. 19 (UPI) -- American fighter planes were scrambled in northeast Syria on Thursday after government airstrikes hit close to U.S. and coalition special forces' positions, the Pentagon said.
According to military officials, the strikes were launched by Syrian Su-24 fighter jets flying over Hasakah. U.S. special forces were conducting operations in the area at the time of the bombings, Pentagon spokesman Capt. Jeff Davis said in a news release.
The operations were part of Operation Inherent Resolve, the U.S. military's central effort against the Islamic State militant group in both Syria and Iraq -- a campaign that's supported by Bashar Assad's regime and their top ally, Russia.
"It troubles us when we see ... [Assad] regime airstrikes in Hasakah in an area where it's well known by everybody that the coalition is actively engaged in operations against the Islamic State," Davis said.
It's unclear where the U.S. planes were scrambled from, for security reasons, but the Pentagon maintains a fleet of Air Force F-15 Eagles at Incirlik Air Base in Turkey.
"We view instances that place coalition personnel at risk with the utmost seriousness, and we do have the inherent right of self-defense when U.S. forces are at risk," he added.
The Pentagon said in the days before the airstrikes, Syrian ground troops had also launched ground artillery attacks -- causing U.S. and coalition forces to be concerned about risks to their safety.
American officials said Friday they're confused why Damascus would order aerial assaults against groups that are fighting on the same side of their battle.
Thursday, in fact, was the first time American fighter aircraft were scrambled in response to a Syrian government attack against the anti-terrorist Kurdish YPG -- also known as the People's Protection Units -- which operates in the north.
Davis said coalition forces attempted to reach the pilots of the Russian-made jets on the appropriate radio frequency but got no response -- leaving them confused as to the bombers' intentions. They did speak with Russian commanders, however, who assured U.S. forces they were not responsible for the attacks.
"We immediately contacted the Russians ... via our established channel used for de-confliction of airspace and to ensure the safety of coalition forces and their counter-ISIL efforts, and they assured us the aircraft were not Russian," he said.
The Pentagon said it's stepped up air patrols to maximize troops' safety.
"As we've said in the past, the Syrian regime would be well-advised not to interfere with coalition forces or our partners," Davis said.