WASHINGTON — Iranians fired a total of 16 missiles Tuesday in the latest strikes against American forces in Iraq, Defense Secretary Mark Esper and Gen. Mark Milley, the chairman of the Joint Chiefs of Staff, told reporters Wednesday.

Eleven hit the Ain al-Asad air base in Iraq’s western Anbar province and one targeted a base in Irbil in Iraq’s semi-autonomous Kurdish region. The missiles were described as likely short-range with 1,000 to 2,000 pound warheads. Four failed to detonate, they said.

Milley added that the Pentagon believes that Iran fired the missiles with the intent “to kill personnel.” He praised early warning systems, which detected the incoming ballistic missiles well in advance, providing U.S. and coalition forces adequate time to take shelter at both bases.

Officials also said that the U.S. was aware of preparations for the attack. It’s unclear if any intelligence identified specific targets or was more general.

Ain al-Asad was first used by American forces after the 2003 U.S.-led invasion that toppled dictator Saddam Hussein, and it later was used by American troops in the fight against the Islamic State group. It houses about 1,500 U.S. and coalition forces. Trump visited it in December 2018, making his first presidential visit to troops in the region. Vice President Mike Pence visited both Ain al-Asad and Irbil in November.

Trump spoke of new sanctions on Iran, but it was not immediately clear what those would be. The primary agencies involved in implementing such penalties – the departments of Commerce, State and Treasury – do not preview those actions to prevent evasion.

Since withdrawing from the 2015 nuclear deal, the administration had already imposed harsh sanctions on nearly every significant portion of Iran’s economic, energy, shipping and military sectors.

Wednesday’s efort to deescalate the conflict came after world leaders, including Turkish President Recep Tayyip Erdogan and Russian President Vladimir Putin, appealed for restraint.

The fallout for Trump’s order to kill Soleimani had been swift.

Iraq’s Parliament voted to expel U.S. troops from Iraq, though Trump said they would not be leaving.

Trump and top national security officials have justified the Soleimani drone strike with general statements about the threat posed by the general, who commanded proxy forces outside Iran and was responsible for the deaths of American troops in Iraq.