Donald Trump has said "all is well" as he confirmed two US bases in Iraq have been attacked by Iran.
Iran has launched dozens of ballistic missiles at US targets throughout Iraq, including Erbil in northern Iraq and the al-Assad air base in the west of the country in revenge for the killing of General Qassem Soleimani.
Iran's Revolutionary Guard has confirmed it is behind the revenge attacks and has warned the US and regional allies against retaliating with Iran reportedly calling the attack Operation Martyr Soleimani.
He said: "All is well! Missiles launched from Iran at two military bases located in Iraq. Assessment of casualties & damages taking place now. So far, so good! We have the most powerful and well equipped military anywhere in the world, by far!
"I will be making a statement tomorrow morning."
The White House said earlier tonight that Mr Trump had been briefed and had gone to the Situation Room, with it initially understood he would be addressing the nation.
However, this was later denied by White House spokeswoman Stephanie Grisham and instead the president took to Twitter instead.
Security sources inside Iraq said 30 missiles have been fired at targets all over the country.
Two of the missiles aimed at Erbil, in the north, were hit in mid-air by local air defence systems, the Mirror was told.
CNN is saying Iraqi security officials have said no Iraqi security forces have been injured in the attacks.
While a Guard commander has reportedly told a local TV network the missile attacks were the first step and Tehran will not spare Americans.
But it is not clear if any of the missiles penetrated the defence systems and hit Erbil itself.
Officials had initially confirmed multiple rockets had been fired at Al-Asad in Western Iraq in repeated shellings before other locations were targeted in the country.
It has been reported an aircraft in the American wing runway at Ein Al-Assad has been destroyed.
The Federal Aviation Administration has said it would ban US carriers from operating in the airspace over Iraq, Iran, the Gulf of Oman and the waters between Iran and Saudi Arabia in light of the attacks.
A statement from the Pentagon said: "In recent days and in response to Iranian threats and actions, the Department of Defense has taken all appropriate measures to safeguard our personnel and partners. These bases have been on high alert due to indications that the Iranian regime planned to attack our forces.
"It is clear that these missiles were launched from Iran and targeted at least two Iraqi military bases hosting U.S. military and coalition personnel at Al-Assad and Irbil. We are working on initial battle damage assessments.
"As we evaluate the situation and our response, we will take all necessary measures to protect and defend U.S. personnel, partners, and allies in the region."
