Washington | Jagran News Desk: The United States on Friday issued a travel advisory to its nationals in Iraq asking them to depart immediately due to the heightened tensions following the killing of Iran's elite Quds Force chief, General Qassem Soleimani in a US airstrike.

“US citizens should depart via airline while possible, and failing that, to other countries via land,” read a statement by the Embassy.

The US strike hit outside Baghdad airport early Friday but security sources told AFP it was still open to flights.

Iran warned of "severe revenge" and said arch-enemy the United States bore responsiblity for the consequences after killing one of its top commanders. 

The Islamic Revolutionary Guard Corps confirmed the commander of its Quds Force foreign operations arm had been killed by US forces in Baghdad, with Foreign Minister Mohammad Javad Zarif denouncing it as a "dangerous escalation".

General Soleimani, the head of Iran's elite al-Quds force and architect of its regional security apparatus, was killed following a US airstrike at Baghdad's international airport on Friday. The strike also killed the deputy chief of Iraq's powerful Hashed al-Shaabi paramilitary force.

Following Soleimani's death, President Trump, now on vacation in Florida, did not comment immediately, except for tweeting an image of the US flag.

The strike comes days after Trump threatened Tehran after Iraqi supporters of pro-Iranian regime factions laid siege to the US embassy in Baghdad, following deadly American air strikes on a hardline Hashed faction.

The Pentagon alleged that the strike was aimed at deterring future Iranian attack plans.

"General Soleimani was actively developing plans to attack American diplomats and service members in Iraq and throughout the region. General Soleimani and his Quds Force were responsible for the deaths of hundreds of American and coalition service members and the wounding of thousands more,” it alleged.

It said that Soleimani had "orchestrated" attacks on coalition bases in Iraq over the last several months - including the attack on December 27 - culminating in the death and wounding of additional American and Iraqi personnel.

“General Soleimani also approved the attacks on the US embassy in Baghdad that took place this week,” it said.

“The United States will continue to take all necessary action to protect our people and our interests wherever they are around the world,” it said.

Reacting to Soleimani's death, Iran said the country and the "free nations of the region" will take revenge on the United States.

"There is no doubt that the great nation of Iran and the other free nations of the region will take revenge for this gruesome crime from criminal America," President Hasan Rouhani said, referring to Iran's allies across the Middle East.

Soleimani's "martyrdom ... by the aggressor and criminal America has saddened the heart of the nation of Iran and all the nations of the region," he said in a statement posted on the Iranian government website.

His death had "redoubled the determination of the nation of Iran and other free nations to stand against America's bullying and defend Islamic values", he said.

(With inputs from agencies)