Defence Secretary Mike Esper and US Secretary of State Mike Pompeo arrived at the White House Tuesday to discuss the attacks, according to Reuters.
"Iran launched more than a dozen ballistic missiles against US military and coalition forces in Iraq. It is clear that these missiles were launched from Iran and targeted at least two Iraqi military bases hosting US military and coalition personnel at Al-Assad and Irbil. We are working on initial battle damage assessments," Defence Department spokesperson Jonathan Hoffman said in a statement Tuesday.
"As we evaluate the situation and our response, we will take all necessary measures to protect and defend US personnel, partners, and allies in the region," the statement adds.
Ayn al-Asad Air Base in western Iraq, which houses a large US airbase, has been hit by several rockets following a strike carried out by Iran's Islamic Revolutionary Guard (IRGC) as "revenge" for the killing of Iranian Quds Force commander Gen. Qasem Soleimani.
"We warn all allied countries of the US that if attacks are launched from bases in their countries on Iran, they will be a target of military retaliation," the IRGC said in a statement obtained by the New York Times' Farnaz Fassihi.
US President Donald Trump said on Tuesday the US is prepared for any retaliation on the side of Iran and that Washington is ready to retaliate in return.
The US president's remarks came just days after he tweeted about the possible targeting of 52 cultural sites in Iran - a number that symbolizes 52 Americans held hostage in the US Embassy in Tehran back in 1979.