Iranian state television said on Wednesday that at least 80 'American terrorists' were killed in attacks involving 15 missiles launched by Tehran on U.S. targets in Iraq, adding that none of the missiles were intercepted.

State TV, citing a senior Revolutionary Guards source, also said Iran had 100 other targets in the region in its sights if Washington took any retaliatory measures.

It also said U.S. helicopters and military equipment were 'severely damaged.'

But a U.S. military official said there were no immediate reports of American casualties.

Iran launched missile attacks on American-led forces in Iraq in the early hours of Wednesday in retaliation for the U.S. drone strike which killed Iranian general Qassem Soleimani.

U.S. troops reportedly had early warnings of the missile launches and were able to the sound the alarms at at least one of the two targeted bases.

Iran targeted the U.S. late Tuesday by firing more than a dozen ballistic missiles at two military bases in Iraq housing American troops

The Ain al-Asad airbase in western Iraq and the Erbil base in Iraqi Kurdistan were both struck by the missiles on Tuesday at about 5.30pm (EST)

Those in harm's way were able to scramble to safety and hide in bunkers during the attack, the official told USA Today.

Al-Asad and Erbil bases were both targeted in the attack. U.S. troops had been practicing safety drills for some time.

Iraqi officials say there were no casualties among their forces either.

President Donald Trump tweeted that 'all is well' and 'so far so good' as the damage and casualties continued to be assessed.

Ain al-Asad air base was first used by American forces after the 2003 U.S.-led invasion that toppled dictator Saddam Hussein, and later saw American troops stationed there amid the fight against the Islamic State group in Iraq and Syria.

It houses about 1,500 U.S. and coalition forces.

The al-Asad base for American and coalition troops (pictured above in December) was struck by missiles 'clearly launched from Iran', U.S. officials say

The Erbil base in Iraqi Kurdistan, which provides facilities and services to at least hundreds of coalition personnel and CIA operatives, was also hit in the missile attack

About 70 Norwegian troops also were on the air base but no injuries were reported, Brynjar Stordal, a spokesperson for the Norwegian Armed Forces said.

The rockets used in the attack, according to Iranian TV, were Fatteh-110 ballistic missiles, which have a range of 186 miles or 300km.

The Pentagon had earlier said the missiles were 'clearly launched from Iran' to target U.S. military and coalition forces.

The Pentagon said it was still working to assess the damage.

President Donald Trump says 'all is well' and 'so far so good' as the damage and casualties continue to be assessed after Iran fired more than a dozen ballistic missiles at two Iraqi bases housing American troops

Iran's foreign minister Javad Zarif called the attacks 'self-defense' but said they did 'not seek escalation' but would defend itself against further aggression

'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,' a statement from the Pentagon read.

'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.'