Baghdadinfo-icon: Iraninfo-icon struck back at the United Statesinfo-icon early Wednesday, firing a series of ballistic missiles at two military bases in Iraqinfo-icon housing American troops in the first act of the Islamic republic's promised revenge for the USinfo-icon killing of a top Iranian general.

It was Iran's most direct assault on Americainfo-icon since the 1979 seizing of the US Embassy in Tehraninfo-icon, and Iranian state TVinfo-icon said it was in revenge for the US killing of Soleimani, whose targeted assassination in Baghdad by US forces prompted angry calls to avenge his slaying.

"In Operation Martyr Soleimani in the early hours of Wednesday, tens of ground-to-ground missiles were fired at the U.S. base and successfully pounded Ain al-Asad Base," Iran's Islamic Revolutionary Guard Corps said in an official statement.

It said the shelling "is merely the beginning of a series of revenge attacks with no deadline for when it ends," it said.

"We warn all allied countries of the U.S. that if attacks are launched from bases in their countries on Iran, they will be a target of military retaliation," it added.

The Pentagon confirmed that the attacks occurred at approximately 5:30 p.m. (EST) on Tuesday.

"Tens of surface-to-surface missiles" were fired at the strategic airbase and the attack was later confirmed by the US officials. 

"We warn US allies providing bases for the [American] terrorist armyinfo-icon... that any country serving as the origin of bellicose and aggressive attacks in any form against the Islamic Republic of Iran will be targeted," read the IRGC statement.

The statement, according to Tasnim news agency, also said that Tehran sees no difference between the "Zionist regime" - meaning Israelinfo-icon - and the US when it comes to the "crime" of assassinating Soleimani. This was presumably in reaction to reports that Israeli PM Benjamin Netanyahu was trying to disassociate from the strike, calling it a purely American affair.

The strike comes as no surprise since Iran had vowed to take a "harsh revenge" in the wake of the US terror attack.

The Iranians fired a total of 15 missiles, two US officials said. Ten hit Ain al-Asad and one the base in Erbil according to The Associated Press.

Two Iraqi security officials said at least one of the missiles appeared to have struck a plane at the Ain al-Asad base, igniting a fire. There were no immediate reports of casualties from the attacks.

According to Iranian state television, 80 "American terrorists" were killed in the missileinfo-icon attack, 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 US helicopters and military equipment were "severely damaged".

Sirens were reportedly heard and American helicopters flew over the airbase and the total alert was activated, reports from Baghdad said.

"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," White House spokeswoman Stephanie Grisham said in a statement.

Iran's Foreign Minister, Javad Zarif, tweeted a statement that said: "We do not seek escalation or warinfo-icon, but will defend ourselves against any aggression".

Iran took & concluded proportionate measures in self-defense under Article 51 of UN Charter targeting base from which cowardly armed attack against our citizens & senior officials were launched.

'Slap' on 'American faces'

Hours after the attack, Iranian Supreme Leader Ayatollah Ali Khamenei in an address to the nation said: "We slapped them (Americans) on the face last night". He added that military action was not enough.

Ayatollah Khameneiinfo-icon added that the "corrupt presence of the US in the region should come to an end", saying it has caused war, division, and destruction.

Iran's supreme leader also invoked the virtues of the slain commander, Gen Soleimani, saying he was a "great, brave warrior" and dear friend to us.

Iranian President Hassan Rouhani too addressed the nation after the attacks and said that the US may have "cut off Soleimani's arm" but Iran will respond by "cutting off your leg" in the region, Fars newsinfo-icon agency reported.

Major escalation

The brazenness of the strike was highly unusual for Iran, experts say. This time, conventional, rather than guerrilla-style weaponsinfo-icon were used and responsibility was rapidly claimed.

"It is a major escalation. Ballistic missiles openly launched from Iran onto American targets is a new phase," said Middle Eastinfo-icon expert Phillip Smyth.

"This is probably not the only response that is going to come.... This is just a big, public one in terms of sending a signal."

Trump did not go on evening television to address the nation -- something of an informal presidential tradition in times of foreign policyinfo-icon crises -- in the immediate hours following Iran's missile strikes.

In a bizarre tweet however, Donald Trumpinfo-icon 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 worldinfo-icon, by far! I will be making a statement tomorrow morning."

Oilinfo-icon prices jumped up after the attack. US crude was up 1.2 per cent to more than $63 a barrel, coming down slightly from a 4 per cent spike earlier. Gold reached a six-year high as worried investors headed for safe-haven assets.

Stock markets in Hong Konginfo-icon and Chinainfo-icon also fell on opening.

In the US, the aviation regulator banned civil flights over Iraq, Iran and the Gulf, citing the potential for "misidentification" of aircraft.

The slide into open confrontation followed days of sabre rattling between Washington and Tehran, coupled with growing confusion over the future of US troops in Iraq, where many are outraged at the drone strike.

Qassem Soleimani, the head of the IRGC's elite Quds Force, was killed in a U.S. drone strike outside Baghdad International Airport early Friday.

His death marked a dramatic escalation in tensions between the U.S. and Iran, which have often been at a fever pitch since President Donald Trump chose in 2018 to unilaterally withdraw Washington from a 2015 nuclear pact world powers struck with Tehran.

Iranian Supreme Leader Ali Khamenei, who bestowed the country's highest honor on Soleimani last year, vowed "severe retaliation" in response to his killing.