File photo taken on July 11, 2018 shows the Pentagon seen from an airplane over Washington, D.C., the United States. (Xinhua/Liu Jie)

WASHINGTON, Feb. 25 (Xinhua) -- The Pentagon confirmed on Thursday that the U.S. military had conducted airstrikes against infrastructure utilized by Iranian-backed militant groups in eastern Syria.

"At President (Joe) Biden's direction, U.S. military forces earlier this evening conducted airstrikes against infrastructure utilized by Iranian-backed militant groups in eastern Syria," the Pentagon said in a statement.

"These strikes were authorized in response to recent attacks against American and Coalition personnel in Iraq, and to ongoing threats to those personnel," it said, adding the strikes destroyed multiple facilities located at a border control point used by a number of Iranian-backed militant groups.

The Pentagon called the operation a "proportionate military response" carried out after consultations with coalition partners.

"The operation sends an unambiguous message: President Biden will act to protect American and Coalition personnel. At the same time, we have acted in a deliberate manner that aims to de-escalate the overall situation in both eastern Syria and Iraq," the Pentagon said in the statement.

Two rockets landed in the heavily fortified Green Zone in the center of Iraq's capital Baghdad on Monday evening. The attack caused no casualties and was claimed by none.

The Green Zone is where the U.S. embassy is located, and U.S. property together with military bases housing U.S. troops is a frequent target of mortar and rocket attacks.

On Feb. 15, a rocket strike targeted coalition forces near the Erbil International Airport in the semi-autonomous region of Kurdistan in northern Iraq, which houses a U.S.-led coalition military base.

The attack killed one civilian contractor and injured several members of the U.S.-led coalition, including one American service member and several American contractors, according to a statement issued that day by the U.S. State Department.

U.S. Secretary of State Antony Blinken said then that Washington was "outraged" by the attack.

Iran denied any ties with the Feb. 15 attack as well as any other attacks.

Thursday's airstrikes also came at a time when the Biden administration, which reportedly plans to bring the United States back to the 2015 Iran nuclear deal that the Donald Trump administration pulled out of, said it was ready to engage in negotiations with Iran over the nuclear issue.