• Iran has fired a series of missiles at two Iraqi air bases hosting US troops.
• The US said 15 missiles were fired. Ten struck the Ain Assad air base and one a base in Erbil. Four missiles failed to hit their targets.
• It is understood there are few, if any, casualties.
• The attack is retaliation for the killing of Iranian general Qassem Soleimani as tensions between the US and Iran flare.
• Donald Trump has tweeted "All is well" and will release a statement tomorrow.
Iran has struck back at the United States for the killing of a top Iranian general, firing a series of surface-to-surface missiles at an Iraqi air base housing US troops and warning the United States and its allies in the region not to retaliate.
Iran state TV said Tehran had launched missiles at Iraq's Ain Assad air base over America's killing of general Qassem Soleimani.
A second round of attacks started an hour after the first phase took place, Tehran-based Tasnim news agency reported.
A US official confirmed airstrikes at the airbases. The official said there were "very few if any casualties" from the attack on sites in Iraq. It is understood there was enough warning for troops to take cover.
The official said 15 missiles were fired. Ten struck the Ain al-Asad air base in Iraq's western Anbar province. One struck a base in Irbil in Iraq's semiautonomous Kurdish region. Four missiles failed to hit their targets.
The official says the bases are still being searched for casualties.
US President Donald Trump tweeted: "All is well!" this afternoon NZT after the missile attacks. "I will be making a statement tomorrow morning," he said.
A statement from the Pentagon in the United States said Iran had launched more than a dozen ballistic missiles against US and coalition military 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 [Ain Assad] and Irbil," said a statement from Jonathan Hoffman, an assistant to the US Secretary of Defense for Public Affairs.
"We are working on initial battle damage assessments ... as we evaluate the situation and our response, we will take all necessary measures to protect US personnel, partners and allies in our region," he said.
Iranian state TV described it as Tehran's revenge operation over the killing of Soleimani, the leader of the Revolutionary Guard.
"The fierce revenge by the Revolutionary Guards has begun," Iran's Islamic Revolutionary Guard Corps said in a statement on a Telegram channel.
Iran's Revolutionary Guard warned the US and its regional allies against retaliating over the missile attack against the Ain Assad air base in Iraq's western Anbar province.
The Guard issued the warning via a statement carried by Iran's state-run IRNA news agency.
"We are warning all American allies, who gave their bases to its terrorist army, that any territory that is the starting point of aggressive acts against Iran will be targeted," The Guard said.
"This time we will respond to you in America."
The Iranian government also warned that, in the event Iranian soil is bombed, it will retaliate against America's allies in the Middle East by striking Dubai and Haifa.
White House press secretary Stephanie Grisham said the White House was aware of the attacks.
"The President has been briefed and is monitoring the situation closely and consulting with his national security team," she said.
He had been planning to give an address but later decided not to.
Iraq's Joint Military Command said seven rockets had hit the Ain Assad air base. Iranian officials said the attack began at 1.20am, the time that Soleimani was killed by an American drone at the Baghdad airport on Friday.
State TV said the operation's name was "Martyr Soleimani". It said the Guard's aerospace division, which controls Iran's missile programme, launched the attack. Iran said it would release more information later.
Hossein Soleimani, the editor in chief of Mashregh, the main Revolutionary Guards news website, said that more than 30 ballistic missiles had been fired at the American base at Ain Assad.
There were also rockets fired at an American base in Erbil, in northern Iraq.
Ain Assad air base is in Iraq's western Anbar province. It was first used by American forces after the 2003 US-led invasion that toppled dictator Saddam Hussein.
It later saw American troops stationed there amid the fight against the Islamic State group in Iraq and Syria.
The attack comes after a stampede broke out after the funeral for Soleimani in his hometown of Kerman, and at least 56 people were killed and more than 200 were injured as thousands thronged the procession, Iranian news reports said.
As the crowds mourned, more angry calls rose from Iran to avenge his death, drastically raising tensions in the Middle East.
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Iran had promised retaliation of Soleimani's death after he was killed in the US drone strike.
New Zealand Defence Minister Ron Mark this afternoon said he had not been briefed, with news of the attack breaking while he was speaking to reporters.
Minutes earlier, Mark told media that while there was concern about growing tension, an early withdrawal of troops was not being considered.
The Government currently has a deadline of June by which to pull out New Zealand's soldiers, who have been training Iraqi troops at Camp Taji, north of Baghdad.
Mark said the focus needed to remain on deescalating the tension in the region.
"We are, as always, very clear about our responsibility to maintain good situational awareness around security," Mark said on Wednesday.
"We have stringent security measures in place."
-with AP, New York Times