It is the first time the United States has announced a strike on Iranian proxy forces in Iraq after targeting Tehran-linked sites in Syria on three occasions in recent weeks, in response to a spike in attacks on American personnel.

"We can confirm an attack last night by Iran-backed militias using a close-range ballistic missile against US and coalition forces at Al-Asad Airbase, which resulted in eight injuries and some minor damage to infrastructure," Pentagon spokesman Brigadier General Pat Ryder said in a statement.

The Ain al-Asad Air Base is located in the desert of Iraq's Western Anbar province and hosts forces of the US-led coalition fighting the Islamic State (IS) group in Iraq.

"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 several enemy KIA (killed in action)," Ryder said.

The surge in attacks on American troops is linked to the latest round of conflict between Israel and Hamas, which began when militants from the Palestinian group carried out a shock cross-border attack from Gaza on October 7 that Israeli officials say killed about 1,200 people.

Israel has responded with a relentless air, land and sea campaign against Hamas that the Gaza health ministry says has killed more than 14,000 people.

Those deaths have sparked widespread anger across the region, and Israel's campaign against Hamas has repeatedly been cited as justification for attacks on American personnel in Iraq and Syria that have left scores of US troops injured.

Deputy Pentagon Press Secretary Sabrina Singh told reporters on Tuesday that US forces "have been attacked approximately 66 times since October 17 -- 32 separate times in Iraq and 34 separate times in Syria."

The attacks have resulted in approximately 62 injuries to US personnel, Singh said, noting that the number does not yet include the eight cited by Ryder, since that most recent missile strike is still being evaluated.

While American forces have been targeted in both Iraq and Syria, Washington had until now only responded with strikes in Syria in an apparent bid to avoid inflaming political tensions in Iraq, which the US invaded in 2003 and where Iran wields substantial influence.

A source from the Hashed al-Shaabi or Popular Mobilization Forces -- mainly pro-Iranian units now integrated in the regular armed forces -- had earlier confirmed that a strike on a vehicle had killed one fighter and wounded three others.

The strike hit a vehicle belonging to a pro-Iran group in a convoy traveling along the motorway through Abu Ghraib, 30 kilometers (20 miles) west of Baghdad.

A group called "the Islamic resistance in Iraq" said Tuesday that one of its fighters was killed, without elaborating on the circumstances of his death and without saying if he was killed in Abu Ghraib.

His funeral was held in a Baghdad mosque on Tuesday afternoon and hundreds of fighters from the Hashed al-Shaabi attended the ceremony, according to an AFP journalist.

There are roughly 2,500 American troops in Iraq and some 900 in Syria as part of efforts to prevent a resurgence of the Islamic State group.