The US struck two facilities used by Iran-backed militias in Jurf al-Nasr in Iraq early Wednesday morning, after the militias continued rocket and drone attacks against US forces in the region on Tuesday.
Initial reports by Iraqi media indicated that several militants were killed in the strikes.
US CENTCOM stated that it conducted "discrete, precision strikes" against two facilities in Iraq, adding that "the strikes were in direct response to the attacks against US and Coalition forces by Iran and Iran-backed groups, including the one in Iraq on November 21, which involved use of close-range ballistic missiles."
The attack came just hours after at least five militants from the Iran-backed Kataib Hezbollah militia in Iraq was killed in a US airstrike in response to a ballistic missile attack against the Ain al-Assad base in Iraq, where US forces are hosted, according to CENTCOM and reports by Iraqi media.
CENTCOM reported on Tuesday that an AC-130 gunship targeted militants responsible for a missile attack against Ain al-Asad Air Base. The strike against the militants resulted in several casualties, according to CENTCOM.
Kataib Hezbollah announced on Tuesday that an operative in the Iran-backed militia named Fadel al-Maksusi had been killed in the US strike.
Iran-backed militias threaten further escalation
Harakat Hezbollah al-Nujaba, another Iran-backed militia in Iraq, warned after the strike that the US would "pay the price for its brutal crimes, and they will receive double the punishment for their crime in the near future."
Iran-backed militias claimed that they had conducted a number of rocket and drone attacks against bases hosting US forces in the region on Tuesday, including Ain al-Assad and a base in al-Shaddadi in Syria.
Deputy Pentagon Press Secretary Sabrina Singh told reporters that the ballistic missile attack that targeted Ain al-Assad caused several non-serious injuries and some minor damage to infrastructure.
"Immediately following the attack, a US military AC-130 aircraft in the area conducted a self-defense strike against an Iranian-backed militia vehicle and a number of Iranian-backed militia personnel involved in this attack. This self-defense strike resulted in some hostile fatalities," said Singh.
The Pentagon spokesperson added that US forces have been attacked about 66 times in Iraq and Syria since October 17, with at least 62 US personnel injured.
Iraqi security forces opened fire on a drone above Baghdad's heavily fortified Green Zone on Tuesday, police and the army said.
It was not clear if the drone was armed, but one Iraqi military officer said initial assessment suggests the drone was on a surveillance mission.
The drone flew away amid the heavy gunfire to down it, the sources said.
The Green Zone in the Iraqi capital houses the US embassy, other missions and government offices.
Reuters contributed to this report.