PENTAGON — The Pentagon says the U.S. military carried out a strike in “self-defense” in eastern Syria on Tuesday, destroying several weapons systems. Pentagon press secretary Major General Pat Ryder told reporters that the military struck three truck-mounted multiple rocket launchers, a T-64 tank and mortars that presented a “clear and imminent threat to U.S. and coalition forces” in the vicinity of Military Support Site Euphrates. “The self-defense strike occurred after the mobile multiple rocket launchers fired rockets in the vicinity of MSS Euphrates and mortars were fired toward U.S. forces,” he said, adding that the strike was “not linked to any broader activities in northwest Syria by other groups.” Ryder said the U.S. was “still assessing” who was operating the weapons that were struck on Tuesday. The U.S. was aware of Syrian military forces that operate in the area and Iranian-backed militia groups in the area that have conducted attacks on MSS Euphrates in the past, according to Ryder, but could not confirm who was responsible for Tuesday’s attack. U.S. forces are in Syria to help Syrian Democratic Forces prevent the Islamic State group from resurging. Last week, U.S. Central Command forces used A-10 fighter aircraft to hit a target threatening U.S. and coalition forces at MSS Euphrates. “Individuals were observed preparing a rocket rail,” Ryder told reporters. David Adesnik, vice president of research at the Foundation for Defense of Democracies, said the U.S. should not consider pulling out its forces from Syria in response to increased fighting across the country, especially if it wants to keep the pressure on Islamic State. He said the terror group has already been “substantially more effective” in areas under the control of Syrian President Bashar Assad. “We are the ones sort of keeping the cork in the bottle. ISIS would have a lot more room for maneuver. … It doesn’t get much coverage, but they are inflicting pain on Assad’s troops,” Adesnik said. ISIS is another name for the Islamic State group.