At least 12 coalition personnel were also injured late Wednesday by a barrage of rockets targeting Camp Taji base, located 27 kilometers north of Baghdad, according to a U.S.-led coalition statement.
A truck rigged with 107 mm Katyusha rocket launchers was discovered by Iraqi security forces a few kilometers from the base following the attack.
A military statement from Iraq’s joint operations command said caretaker Prime Minister Adel Abdul-Mahdi ordered the investigation into what he called “a very serious security challenge and hostile act.”
The United Nations condemned the attack, saying it took “critical political attention away” from Iraq’s ongoing domestic challenges, which threaten to create power vacuum at the seat of Iraq’s government.
Heightened tensions between the United States and Iran in recent months were set in motion by a rocket attack in December on an Iraqi base that killed a U.S. contractor. American airstrikes targeting the Iran-backed militia Kataib Hezbollah followed, which led to protests at the U.S. embassy in Baghdad.
A U.S. drone strike in Baghdad then killed Iranian Gen. Qassem Soleimani, a top commander responsible for expeditionary operations across the wider Mideast. Iran struck back with a ballistic missile attack on U.S. forces in Iraq, the Islamic Republic’s most direct assault on America since the 1979 seizing of the U.S. Embassy in Tehran.
Wednesday’s attack coincided with what would have been Soleimani’s birthday.
There are at least 5,200 U.S. troops in Iraq, training and advising Iraqi forces as part of a global coalition.
Iraqi and United Nations officials scrambled Thursday to contain the fallout from an unprecedented rocket attack that killed three US-led coalition members and threatened yet another escalation of Iran-US tensions.
Fearing an even bloodier flare-up this time, Iraqi officials and the United Nations were quick to condemn the deaths.
Iraq’s military command said it was “a serious security challenge” and pledged to open an investigation.
President Barham Saleh and parliament speaker Mohammed al-Halbussi condemned a “terrorist attack” which targeted “Iraq and its security.”
The UN mission in Iraq called for “maximum restraint on all sides”.
Wednesday’s attack was the 22nd on US interests in Iraq since late October.