The Pentagon is suggesting that Monday's rocket attack against U.S. forces in Syria was launched by Iranian-backed militia forces.
"We're all working under the assumption that they (the rockets) were fired by Iran-backed militias or militia. We don't have specific attribution," Pentagon press secretary John Kirby told reporters Tuesday at the Pentagon.
About 34 rockets were fired on Monday at a military base in Deir ez-Zour, Syria, known as Green Village.
"On June 28, U.S. Forces in Syria were attacked by multiple rockets, approx. 34 x 122mm rounds of indirect fire. There were no casualties or injuries to U.S. forces," U.S. Colonel Wayne Marotto, spokesman for the international military intervention against Islamic State, wrote Tuesday on Twitter.
U.S. troops there returned fire with 155-millimeter artillery rounds, Marotto told VOA. The U.S. also fired a hellfire missile from a drone, wounding one attacker, Marotto added via Twitter.
Kirby said the rockets caused structural damage to at least two buildings, without inflicting any casualties.
"We are still assessing the full scope of the damage," he added.
The back and forth of rockets and artillery rounds came hours after the U.S. military said it struck three targets near the border between Syria and Iraq used by Iranian-backed militias to carry out drone attacks on U.S. personnel and facilities.
"I directed last night's airstrikes targeting sites used by the Iranian-backed militia groups responsible for recent attacks on U.S. personnel in Iraq," U.S. President Joe Biden said Monday in the Oval Office.
Late Sunday, the U.S. struck weapons storage and operational facilities used by militias such as Kata'ib Hezbollah (KH) and Kata'ib Sayyid al-Shuhada (KSS), according to a statement from Kirby. Two of the targets were inside Syria, and one was inside Iraq.
"These structures were directly tied to specifically the threat from UAVs (unmanned aerial vehicles) in terms of the logistics and maintenance of them, the command and control of them, launching and recovering of them and perhaps even transfers of equipment and systems support," Kirby told reporters Tuesday.
"The attacks against our troops need to stop, and that is why the president ordered the operation last night in self-defense of our personnel," White House press secretary Jen Psaki said Monday.
U.S. troops in Iraq have come under attack from drone strikes three times in a "little over a month," General Frank McKenzie, head of U.S. Central Command, told VOA in an interview in Cairo on June 15. The attacks resulted in no casualties.
WATCH: General Frank McKenzie Talks to VOA About Drone Threat in Iraq
Navy Commander Jessica McNulty, a Pentagon spokesperson, added on Monday that "Iran-backed militias have conducted at least five one-way UAVs against facilities used by U.S. and coalition personnel in Iraq since April, as well as ongoing rocket attacks against U.S. and coalition forces."
"The United States does not seek conflict with Iran, but we are well-postured to defend our forces around the region and respond to any threats or attacks," she said.
Iraqi Prime Minister Mustafa al-Kadhimi has condemned the U.S. airstrike on its soil, calling it a violation of national sovereignty that breached international conventions. Iraq's military said its country should not be an arena "for settling scores."
Sunday's strikes were the second time the Biden administration has ordered attacks against Iranian-backed groups. In late February, the U.S. targeted buildings in Syria belonging to what the Pentagon said were Iran-backed militias responsible for attacks against U.S. and allied personnel in Iraq.
