Iran launched over a dozen ballistic missiles targeting at least two bases where US military and coalition forces' are stationed in Iraq, which Tehran said was a "slap in the face" of America.
According to Iranian state TV, the attacks were in revenge for the killing of the commander of Iran's powerful Revolutionary Guards, General Qasem Soleimani, in a US drone strike on Friday, which was ordered by President Donald Trump.
While the Iranian state television claimed that "at least 80 terrorist US soldiers" were killed in the strikes, the Pentagon said it is working on initial battle damage assessments. Some 5,000 US soldiers are in Iraq as part of the international coalition against the IS terror group.
The Iraqi military in a statement said a total of 22 missiles hit two bases housing US troops, but there were no victims among the Iraqi forces.
Shortly after the missile attacks, Trump tweeted, "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."
Iran's supreme leader Ayatollah Ali Khamenei said the attacks were a "slap in the face" of the US.
In a speech broadcast live on state television, Khamenei said, "Last night, a slap in the face was delivered."
US officials said President Trump has been briefed and he is monitoring the situation.
"We are working on initial battle damage assessments," Pentagon spokesperson Jonathan Hoffman said.
Hoffman said around 5:30 pm on January 7, "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, he said.
White House Press Secretary Stephanie Grisham said the President has been briefed about the situation.
We are aware of the reports of attacks on US facilities in Iraq. The President has been briefed and is monitoring the situation closely and consulting with his national security team, Grisham said.
Hoffman said in recent days and in response to Iranian threats and actions, the Department of Defence has taken all appropriate measures to safeguard its personnel and partners.
These bases have been on high alert due to indications that the Iranian regime planned to attack our forces and interests in the region, he said.
"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, Hoffman said.
President Trump spoke with Qatari Emir Sheikh Tamim bin Hamad Al Thani and thanked him for his country's strong partnership with the US. The two leaders discussed the situation in Iraq and Iran, as well as other critical bilateral and regional issues, the White House said.
Trump also telephoned Germany Chancellor Angela Merkel and the two leaders discussed the security situation in the Middle East and Libya and agreed to continue close coordination moving forward, it said.
State Department spokesperson Morgan Ortagus said Secretary of State Michael Pompeo telephoned Kurdistan Regional Government Prime Minister Masrour Barzani and updated him on the Iranian missile attacks on Iraqi air bases, including in Erbil.
The two leaders agreed to stay in close touch as the situation develops.
General Soleimani, who was considered a terrorist by the US, was killed when a drone fired missiles into a convoy that was leaving the Baghdad International Airport on Friday last week.
In an interview with Fox and Friends news show, Pompeo said, "He's a military commander who was actively engaged in plotting to kill Americans in the region. We had an important set of underlying reasons to take this strike. It was wholly lawful. We're confident that we not only got it right legally but we got it right strategically."
The strike also killed the deputy chief of Iraq's powerful Hashed al-Shaabi paramilitary force Abu Mahdi al-Muhandis and some local Iran-backed militias.
Khamenei has vowed a revenge against the killing of his general, saying "severe revenge awaits the criminals" behind the attack.
Soleimani was widely seen as the second most powerful figure in Iran after the Supreme Leader Khamenei. His Quds Force, an elite unit of the Iranian Revolutionary Guards, reported directly to the Khamenei and he was hailed as a heroic national figure.