US carries out defensive airstrike in Iraq: Officials

The U.S. military conducted a defensive airstrike south of Baghdad, Iraq, on Tuesday, according to two U.S. officials.

"U.S. forces in Iraq conducted a defensive airstrike in the Musayib in Babil Province, targeting combatants attempting to launch one-way attack uncrewed aerial systems (OWAUAS)," one of the officials told ABC News.

"Based on recent attacks in Iraq and Syria, U.S. Central Command assessed that the OWAUAS posed a threat to U.S. and Coalition Forces," the official said.

Earlier on Tuesday, Iraqi officials had reported blasts in an area south of Baghdad that is a hub for Iraq's Popular Mobilization Forces, the umbrella name for Iranian-backed militia groups operating under Iraq's Defense Ministry.

A statement provided to ABC News by the Popular Mobilization Authority said, "Forces affiliated with the 47th Brigade… were exposed to an explosion of unknown nature, which resulted in the martyrdom of a number of people and the injury of others."

Tuesday's U.S. airstrike was the first one in Iraq since February, when a drone strike killed a top leader of one of the Iranian-backed militia groups the U.S. had held responsible for close to 170 rocket and drone attacks against U.S. bases in Iraq and Syria.

The attacks against U.S. bases ceased after that airstrike, with the exception of two attacks in April, but there have been a series of new attacks over the past week.

Unlike previous U.S. airstrikes in Iraq and Syria that were in retaliation for the attacks on U.S. bases, Tuesday's airstrike was described as defensive and targeting militants preparing to undertake an attack.

These pre-emptive airstrikes have become commonplace in Yemen, where the U.S. has been targeting Houthi militants preparing attacks against commercial shipping around the Red Sea.

It is unclear if Tuesday's airstrike will lead to similar activity should militants continue targeting U.S. bases.

But a U.S. official indicated that Tuesday's airstrike underscored the U.S. commitment to protecting its personnel and said, "We maintain the inherent right to self-defense and will not hesitate to take appropriate action."

There are still 2,500 U.S. troops in Iraq and about 900 serving in Syria, assisting local security forces in preventing the resurgence of ISIS.

Since earlier this year, the U.S. and Iraq have been discussing changes to the continued presence of U.S. troops in Iraq.