The U.S. Army’s 82nd Airborne Division’s alert brigade has been issued orders to deploy rapidly to Kuwait following an attack on the American embassy in Baghdad by a pro-Iranian mob.

At least 750 paratroopers are already making their way to the Middle East, Secretary of Defense Mark Esper confirmed in a statement on Tuesday, saying additional forces are prepared to deploy over the next several days.

'This deployment is an appropriate and precautionary action taken in response to increased threat levels against U.S. personnel and facilities, such as we witnessed in Baghdad today,' said Esper.

A total of 4,000 soldiers from the 82nd Airborne's Deployment Ready Brigade have been put on notice for imminent deployment in the next 96 hours, three U.S. defense officials told Fox News.

The snap deployment comes amid rapidly rising tensions between Iran and the U.S. and a series of violent tit-for-tat escalations between the two countries.

On Tuesday, some 6,000 pro-Iran Shiite militia fighters stormed U.S. embassy in Baghdad, set walls ablaze and chanted 'Death to America!' in a violent retaliation for American air strikes. There were no reports of American casualties, and the attack was repelled after 100 Marines rapidly reinforced the compound.

Secretary of State Mike Pompeo called the attack an act of 'state-sponsored terrorism' in an interview with CBS News, and President Donald Trump vowed that the Iranian government will be held 'fully responsible' for the attack.

Pompeo said in a statement that the attack was 'orchestrated by terrorists' and 'abetted by Iranian proxies', tweeting pictures that he said showed US-designated terrorists with Iranian ties outside the embassy.

US Army 82nd Airborne Division airborne soldiers are seen during an exercise last year. On Tuesday, some 4,000 paratroopers from the unit were ordered to prepare for rapid deployment to the Middle East

Several thousand protesters and militia fighters broke down the gate of the US embassy in Baghdad, storming the compound as gunshots and sirens rang out, following Sunday's US air strikes on Hezbollah that killed 2

Thousands of Kataeb Hezbollah supporters left funerals held for 25 fighters killed by US strikes on Sunday night. They then marched towards the US embassy, pouring through the heavily fortified 'Green Zone' before reaching the gates of the compound. As the mood deteriorated security personnel headed into the building and carnage ensued outside, with rioters eventually tearing through the main gate and inside the main forecourt of the embassy

This map shows the Embassy compound located along the Tigris River in Baghdad, Iraq

'The U.S. Embassy in Iraq is, & has been for hours, SAFE! Many of our great Warfighters, together with the most lethal military equipment in the world, was immediately rushed to the site. Thank you to the President & Prime Minister of Iraq for their rapid response upon request,' Trump tweeted Tuesday evening.

'Iran will be held fully responsible for lives lost, or damage incurred, at any of our facilities. They will pay a very BIG PRICE! This is not a Warning, it is a Threat. Happy New Year!' he added.

In a third tweet he quipped 'The Anti-Bengahzi!' The post was an effort to distinguish his administration's response to that of the Obama administration in the 2012 attack on a diplomatic compound in Libya that left four Americans dead. The tweet, which had a spelling error, was deleted soon after.

In the Tuesday attack militia members with the Shiite, pro-Iranian Popular Mobilization Forces (PMF) swarmed the high-security compound, breaking down the main door to the compound and setting a fire in the reception area, forcing US soldiers inside the embassy to fire tear gas, stun grenades and warning shots. In the chaos 62 of the thousands of fighters were injured, according to PMF.

Ambassador to Iraq Matthew Tueller was on leave at the time of the attack and embassy staff had already been evacuated before the US Marine guard became besieged behind the bullet-proof glass and on the rooftops.

There were no reports of U.S. casualties during the embassy incursion.

The attack on the embassy was is in retaliation for US air strikes on the Iran-backed Kataeb Hezbollah on Sunday night, which killed two dozen fighters. Those strikes were in retaliation for last week's killing of an American contractor at a U.S. base in Kirkuk.

Donald Trump announced that the US embassy in Baghdad is safe after some 6,000 pro-Iran militia fighters stormed the compound on Tuesday, set walls ablaze and chanted 'Death to America!' in a violent retaliation for American air strikes

In a third tweet he quipped 'The Anti-Bengahzi!' The post was an effort to distinguish his administration's response to that of the Obama administration in the 2012 attack on a diplomatic compound in Libya that left four Americans dead. The tweet, which had a spelling error, was deleted soon after

The Department of Defense released this photo showing Marines assigned to Special Purpose Marine Air-Ground Task Force-Crisis Response-Central Command preparing to deploy from Kuwait to support the US embassy in Baghdad

On Tuesday the Pentagon sent 100 additional Marines (above) assigned to Special Purpose Marine Air-Ground Task Force-Crisis Response-Central Command to the Baghdad embassy in Chinook helicopters in wake of the attack

A US Marine pictured preparing to deploy from Kuwait to Baghdad to respond to the crisis outside the embassy

Marines pictured inside military aircraft taking them from Kuwait to Baghdad to reinforce the US embassy

On Tuesday US Defense Secretary Mark Esper said the US was sending additional forces to the Baghdad embassy, while calling on Iraq to help protect American personnel, hours after Trump slammed the attack and warned that Iran will be 'held fully responsible'.

Video footage from the scene shows the US military sending in Marines from Kuwait in two Army Aviation UH-60M utility helicopters and two CH-47F Chinook helicopters, which were then used to evacuate embassy personnel. Another clip shows a US Apache helicopter dropping warning flares above the embassy.

'We have taken appropriate force protection actions to ensure the safety of American citizens, military personnel and diplomats in country, and to ensure our right of self-defense,' Esper said in a statement.

'As in all countries, we rely on host nation forces to assist in the protection of our personnel in country, and we call on the Government of Iraq to fulfill its international responsibilities to do so,' he added.

An AH-64E Guardian attack helicopter was also seen flying over the embassy ready to open fire in case any Kataeb Hezbollah members attacked the incoming Marines.

Militia fighters in military garb pictured setting fire to the US embassy wall and throwing rockets over the fencing

US soldiers fire tear gas onto protesters who broke into the compound as black smoke from fires set by the rioters billows into the air

Protesters and militia members set fire to a reception room in the US embassy during the furious protest condemning US airstrikes on Sunday

A protester holds an Iraqi flag during a protest to condemn air strikes belonging to paramilitary forces on Tuesday. In the ambush US forces fired back with tear gas and stun grenades, wounding dozens

Protesters and militia fighters carry the logo of the US embassy in Baghdad during the massive protest that unfolded Tuesday

This photo taken through a broken window shows a vandalized room in the US embassy in Baghdad after protesters breached the outer wall of the compound

US soldiers could be seen inside the building filmed from the outside by furious protesters who pressed up against the glass taunting the personnel

US embassy security personnel are seen through a glass window as protesters and militia fighters wreak havoc outside

Protesters burned the property in front of the U.S. compound on Tuesday waving flags and banners for their specific groups in protest of the US airstrikes in Iraq on Sunday

The deployed Marines are reportedly from Special Purpose Marine Air-Ground Task Force-Crisis Response-Central Command, a ground force deployed to the Middle East that specializes in crisis response, U.S. officials confirmed to Military.com. That force was created after the 2012 attack on the diplomatic post in Benghazi, Libya, that killed four Americans.

On Tuesday morning Trump condemned the attack on the US embassy and pointed the blame to Iran.

'Iran killed an American contractor, wounding many. We strongly responded, and always will.' Trump tweeted on Tuesday morning. 'Now Iran is orchestrating an attack on the U.S. Embassy in Iraq. They will be held fully responsible. In addition, we expect Iraq to use its forces to protect the Embassy, and so notified!'

'To those many millions of people in Iraq who want freedom and who don’t want to be dominated and controlled by Iran, this is your time!' the president added.

The attack on Tuesday unfolded after thousands attended the funerals of the Iran-backed Kataeb Hezbollah fighters killed in the American airstrikes on Sunday. After the processions, mourners and protesters rushed through the heavily fortified Green Zone without being stopped by Iraqi military as they burned U.S. flags and changed 'Death to America! on their way to the consulate.

There were roughly 6,000 protesters at the height of the demonstrations, a U.S. official estimated, most hailing from Kataeb Hezbollah, also known as Hashd al-Shaabi.

US soldiers watch from behind a smoke screen as Iraqi protesters surround the US embassy building in the capital Baghdad. They fired warning shots, followed by stun grenades and tear gas

A wounded protester is seen held by pro-Iran militia members as chaos unfolds outside U.S. Embassy in Baghdad on Tuesday. The protester may have been wounded by American stun gun fire or in the tumult of the demonstrations

Members of the Hashd al-Shaabi militia, part of the Popular Mobilization Forces of which Kataeb Hezbollah is a member, attempt to break through the gates of the compound on Tuesday

Demonstrators react as tear gas is fired down by US soldiers on the rooftop of the compound after they stormed through the main gate

Demonstrators and members of the militia are seen in the entrance to the compound where visitors and vehicles are usually screened by security forces

A security guard's hut window has been badly damaged by the rioters as smoke spews from fires set around the compound today, with protesters waving flags of the militias part of the Popular Mobilization Forces (PMF). Many are supported by Iran.

Iraqi protesters set ablaze a sentry box in front of the US embassy building in the capital Baghdad to protest against the weekend's air strikes by US planes on several bases belonging to the Hezbollah brigades near Al-Qaim

Men wearing militia uniforms cover their faces while setting fire to the barricades as tear gas is fired over the ramparts on Tuesday

US fighter jets bombarded three locations in Iraq on Sunday night, in retaliation for last week's 36-rocket attack which killed an American contractor and injured several others at a base in Kirkuk, 170 miles north of Baghdad.

On Sunday the US struck a total of five Kataeb Hezbollah controlled weapon depots in Iraq and Syria, killing at least 25 people and wounding 51.

Baghdad had warned the American government that relations with the US were at risk following the airstrikes. There are also concerns over whether Iraqi forces allowed protesters to reach the Embassy, located in a usually restricted area.

The US attack - the largest targeting an Iraqi state-sanctioned militia in recent years - and the calls for retaliation represent a new escalation in the proxy war between the US and Iran playing out in Iraq.

Kataeb Hezbollah, which is separate but linked to the Lebanese Hezbollah, operates under the umbrella of the state-sanctioned predominantly Shiite militias known collectively as the Popular Mobilization Forces (PMF). Many are supported by Iran.

The US says Kataeb Hezbollah is responsible for 11 attacks on US-led coalition bases in the past two months.

Smoke rises from the heavily fortified US embassy as protesters set parts of the compound ablaze and security offers fight back deploying tear gas and stun grenades on Tuesday

Protesters pictured throwing stones towards the embassy on Tuesday while chanting 'Death to America'

A U.S. Embassy security officer is seen as protesters and militia fighters gather to condemn air strikes

It was the first time in years that protesters have been able to reach the US embassy in Baghdad, the nation's largest embassy which spans 104 acres.

The embassy, located in Baghdad's Green Zone, has been placed on lockdown.

Who is the mob storming the embassy? The mob are supporters or members of Kataeb Hezbollah, which is separate but linked to the Lebanese Hezbollah, and operates under the umbrella of the Iraqi government sanctioned umbrella of militias known collectively as the Popular Mobilization Forces (PMF). Many of the groups, but particularly Kataeb Hezbollah, are backed by Iran. Kataeb Hezbollah has for months been firing rockets and mortars at US forces throughout Iraq. It actively stockpiles and smuggles Iranian-made weapons into Iraq. The terror group has in the past received weapons from the Palestinian Hezbollah, which is also a key ally of Iran. Hundreds of the yellow flags of the terror group were seen among the masses on Tuesday.

US Security guards were seen retreating inside the embassy early Tuesday as protesters hurled bottles and smashed security cameras outside the buildings.

Flames rose from the compound as furious rioters pressed up against the bullet-proof windows within the complex, taunting the US soldiers within and spraying pro-Hezbollah graffiti over the glass.

Half a dozen US Marine guards fired warning shots from the rooftops, followed by tear gas and stun grenades, at rioters who set blazes and smashed up barricades on the ground.

Hundreds of angry protesters, many in military fatigues, set up tents outside the embassy and set fire to trailers used by security guards along the embassy wall.

Many were seen carrying posters that read, 'Parliament should oust US troops, or else we will'. Some carried banners with Trump's face crossed out.

Some protesters carried what they said were the coffins of the fighters killed in the American airstrikes. Many were heard chanting 'America, leave, leave!' as per NPR.

Sixty-two people have been reported injured in the carnage by the PMF.

A spokesman for Kataeb Hizbollah said they intend to stake out the street in front of the embassy to push US officials to leave Iraq. 'We will not leave these tents until the embassy and the ambassador leave Iraq,' Mohammed Muhi said, according to the Times.

The US State Department disputed reports of a breach and said all US personnel are safe.

'US personnel are secure and there has been no breach. There are no plans to evacuate Embassy Baghdad,' a State Department spokesperson tells DailyMail.com. 'The US Ambassador to Iraq, Matt Tueller, has been on previously scheduled personal travel for over a week and reports that he has been evacuated are false. He is returning to the Embassy.'

Demonstrators smash a bullet-proof window within the US embassy compound on Tuesday during chilling scenes following a protest over the US bombing of militia sites on Sunday night

Protesters and militia members pictured trying to scale the U.S. Embassy compound in Iraq on Tuesday

Demonstrators smash a bullet-proof window within the US embassy compound on Tuesday during chilling scenes following a protest over the US bombing of militia sites on Sunday night

On Tuesday militia fighters carried coffins they claimed held the members of Kataeb Hezbollah who were killed in the US airstrike through the streets during a funeral in the holy city of Najaf, Iraq that preceded the embassy attack

Hashd al-Shaabi fighters raised a fist in solidarity as they carried the coffins of the slain Kataib Hezbollah militia group members slain in Sunday's US airstrike against the group through the streets on Tuesday

A man on a loudspeaker urged the mob not to enter the compound, saying: 'The message was delivered.'

Later protesters were led by a cleric in prayer, kneeling within the walls of the still-occupied compound, though in an apparently more peaceful demonstration.

Jarring video footage from the scene shows a militia man in a military fatigue pledging to burn down the embassy.

'This is a letter to Trump and the American embassy in Baghdad and its consulate in Erbil and in Basra...those who have attacked our forces and our Jihadi brothers, God willing, if this fire reaches the inside of the embassy, we will not spare a single employee. We are the children of martyrs and this is our statement. Death to America.'

An Iraqi employee at the embassy told the AP that the embassy's security team had evacuated some local staff from a rear gate while others left by helicopter as the rest remained inside 'safe' areas within the embassy.

Iraqi Prime Minister Adel Abdul Mahdi pleaded with the mob against any aggression towards foreign embassies and representations in Baghdad, asking protesters outside the U.S. embassy to leave 'immediately.'

As of Tuesday evening, most of the protesters had dispersed, but many were still outside the embassy in chairs and tents for a sit-in demonstration, challenging US presence in the country and the airstrikes.

In the wake of the attack, President Trump has received regular updates from his national security team while spending the holiday week at Mar-a-Lago in Florida. 'It will be the president’s choice how and when we respond to their escalation,' White House spokesperson Stephanie Grisham said.

Secretary of State Mike Pompeo spoke with Iraqi Prime Minister Adil Abdul Mahdi and President Barham Salih separately by phone from his office in Washington, DC on Tuesday, according to The Hill.

'The secretary made clear the United States will protect and defend its people, who are there to support a sovereign and independent Iraq. Both Abdul-Mahdi and Salih assured the secretary that they took seriously their responsibility for and would guarantee the safety and security of U.S. personnel and property,' a Pompeo spokesperson said.

However, as the news of the embassy riot made headlines, the Iraqi National Security Council released a statement ignoring them and instead condemning the US airstrikes.

Sen. Lindsey Graham Trump's rebuke of Iran for the attack saying, 'there will be no Benghazis on his watch'.

Iraqi protesters holding up a placard with a slogan in Arabic that reads: 'Death to America, Death to Israel' breach the outer wall of the US embassy in Baghdad

US soldiers fire tear gas to halt the protesters, many wearing military fatigues, who stand within the main forecourt of the embassy compound

Iraqi protesters, including members of the Popular Mobilization Forces (Hashed al-Shaabi), a mostly Shiite network of local armed groups trained and armed by powerful neighbor Iran, breach the outer wall of the diplomatic mission

Attack comes seven years after US ambassador was killed in Benghazi attack On September 11, 2012, Islamic militant group Ansar al-Sharia launched a planned attack on US government facilities in Benghazi, Libya. The night time raid killed U.S. Ambassador to Libya J. Christopher Stevens and U.S. Foreign Service Information Management Officer Sean Smith. Stevens was the first US ambassador to be killed in the line of duty since 1979. At 4pm the following day, the militants fired mortars at the CIA annex around a mile away, killing CIA contractors Tyrone S. Woods and Glen Doherty and wounding ten others. Initial analysis found that the attack arose from a protest. But later investigations showed it had been premeditated, although rioters and looters had played an initial role in the chaos. The attack was highly controversial due to accusations that the Obama administration had allowed for security lapses. As Secretary of State, Hillary Clinton later accepted responsibility for security failings following a high level State Department resignation and suspensions of long-standing officials.

'We recall that any aggression or harassment of foreign embassies will be firmly prohibited by the security forces,' Abdel Mahdi's office said several hours after the attack began.

The Iraqi government had earlier announced three days of mourning for the 25 fighters killed in the US strikes.

The United States has around 5,200 troops deployed across Iraq to train security forces and prevent any resurgence of the Islamic State jihadist group.

On Sunday night, US Secretary of State Mike Pompeo had said the strikes send the message that the U.S. will not tolerate actions by Iran that jeopardize American lives.

The Iranian-backed Iraqi militia had vowed Monday to retaliate for the U.S. military strikes in Iraq and Syria that killed 25 of its fighters and wounded dozens.

The attack and vows for revenge raised concerns of new attacks that could threaten American interests in the region.

Kataeb Hezbollah and similar Iran-backed militias play a complicated role in Iraq. The paramilitary has fought against ISIS and is a part of Iraq’s security forces. However, the U.S. has questioned whether the Iraqi government actually has control over it and other Iran-backed groups.

The U.S. attack outraged both the militias and the Iraqi government which said it will reconsider its relationship with the U.S.-led coalition - the first time it has said it will do so since an agreement was struck to keep some U.S. troops in the country.

It called the attack a 'flagrant violation' of its sovereignty.

In a partly televised meeting Monday, Prime Minister Abdul Mahdi told Cabinet members that he had tried to stop the U.S. operation 'but there was insistence' from American officials.

Demonstrators wearing military fatigues and flying the white flag of the Popular Mobilization Forces, of which Kataeb Hezbollah is a member

Milita members and other demonstrators swarm through the security entrance of the US embassy in Baghdad on Tuesday

Demonstrators hurl rocks and shove burning fabric through holes put through the bullet-proof glass surrounding the US embassy complex in the Iraqi capital

US soldiers standing on the rooftops on Tuesday as tear gas and smoke from fires set by the demonstrators rises into the air

U.S. Embassy staff are seen through the glass windows of the compound while the militia members and their supporters gathered outside the building

US military and embassy personnel are seen inside the compound on Tuesday during the ferocious protest outside against US air strikes on Sunday night

Demonstrators in militia uniforms hurl projectiles over the walls of the compound today and throw their terrorist flags over the barbed wire

Demonstrators shove a vehicle over within the walls of the US embassy compound on Tuesday, an Iraqi flag is held aloft as well as the yellow of Kataeb Hezbollah

Iraqi protesters stand on the walls of the US Embassy in Baghdad, protesting Washington's attacks on armed battalions belong to Iranian-backed forces

Iraqi security forces (background) stand guard as protesters, including clerics, hold a prayer inside the walls of the US embassy in Baghdad's Green Zone after the fury died down

Protesters stand on Israeli (left) and US flags (right) which they have also been seen burning on Tuesday amid shouts of 'Down USA' and 'Death to Israel'

Black smoke billows from a fire set outside the entrance to the embassy today as thousands gathered outside the consulate in the Iraqi capital

Flames rise over the compound walls today as hundreds of demonstrators throng in the entrance of the US embassy in the Iraqi capital

US soldiers keeping watch over the rioters on Tuesday after the embassy became surrounded following a furious post-funeral service demonstration for the Iran-backed militia members killed Sunday night

Searing aerial footage was released on Monday of US F-15 Strike Eagles wreaking havoc on Kataeb Hezbollah.

Iran condemned the attack as 'terrorism' while Kataib Hezbollah commander Abu Mahdi al-Mohandes said: 'The blood of the martyrs will not be in vain and our response will be very tough on the American forces in Iraq.'

Meanwhile the Iraqi military spokesman for outgoing Prime Minister Abel Abdel Mahdi rebuked the US for its intervention, General Abdul Kareem Khalaf said: 'We consider it a violation of Iraqi sovereignty and a dangerous escalation that will threaten Iraq and the region.'

The US said it had taken the 'necessary' overnight action to protect its personnel in the region following an attack two days earlier that killed a US civilian contractor and injured four US service members near Kirkuk.

'The Department of Defense took offensive actions in defense of our personnel interests in Iraq', Secretary of Defense Mark Esper said during a press conference at Mar-a-Lago in Palm Beach, Florida.

Another spokesman for the Hezbollah Brigades in Iraq, Sayyed Jaafar Al-Husseini, said: 'Options are kept open as we are waiting for the leadership's decision in this regard. There will certainly be an appropriate retaliation.

'The Americans had tested before the Iraqi resistance strikes, and our capabilities are now duplicated.'

Jewad Kadum, a PMF official, said in a statement that rescue operations were ongoing as well as the evacuation of the wounded, recovery of the dead bodies and the extinguishing of the fire caused by the airstrikes.

U.S. soldiers fire tear gas to stop protesters inside U.S. embassy in Baghdad

Hundreds of protesters are seen on the streets leading to the embassy waving flags and chanting 'Death to America'

raqi protesters set ablaze a sentry box in front of the US embassy building in the capital Baghdad to protest against the weekend's air strikes by US planes on several bases belonging to the Hezbollah brigades near Al-Qaim, an Iraqi district bordering Syria

Protesters and militia fighters gather to condemn air strikes outside the US embassy on Tuesday

Thousands of demonstrators, waving flags of the Shia militia which was decimated in US strikes on Sunday night, swarm outside the embassy on Tuesday

Smoke billows over the horizon on Tuesday as furious demonstrators, some wearing militia uniforms, gathered outside the US embassy on Tuesday

Demonstrators stormed inside the security boxes outside the compound after the personnel withdrew and set fire to the huts

Protesters and militia fighters gather to condemn air strikes on bases belonging to Hashd al-Shaabi (paramilitary forces), outside the main gate of the U.S. Embassy in Baghdad

The locations included weapons storage facilities and command and control locations the group had used to plan and execute attacks on coalition forces, the Pentagon said during an earlier announcement.

Esper, appearing with Secretary of State Mike Pompeo and Chairman of the Joint Chiefs of Staff Mark Milley, said the retaliatory air strikes on Sunday were 'successful' and that all pilots and aircraft involved returned safely.

Iraqi security sources said on Monday that U.S. forces in Iraq's northerly Nineveh province were ramping up security overnight, with U.S.-led coalition jets circling the perimeter of its military bases in Mosul and Qayarah.

The United States had accused the group of a 30-plus rocket attack on Friday that killed the US civilian contractor and injured four US service members and two members of the Iraqi Security Forces near the oil-rich city of Kirkuk.

Pompeo at the news conference said attacks have been going on for 'weeks and weeks weeks'.

The fatal incident was 'the eleventh rocket attack targeting an outpost housing American forces in the last two months,' according to Military Times.

The US fighter jets came in retaliation for 30-plus rocket attack on Friday that killed a US civilian contractor and injured four US service members and two members of the Iraqi Security Forces near the oil-rich city of Kirkuk

These images depict what the U.S. military says are bases of the Kataib Hezbollah militia group that were struck by U.S. forces, in the city of Al-Qa'im, Iraq

The footage shows black smoke being swept across a desert compound after it was struck by fighter jets in last night's raid

F-15 Strike Eagles (like this one seen in a training exercise) hit five targets associated with Kataib Hezbollah, which is an Iranian-sponsored Shiite militia group, said Defense Secretary Mark Esper

'Today what we did is take a decisive response that makes clear what President Trump has said for months and months and months, which is that we will not stand for the Islamic Republic of Iran to take actions that put American men and women in jeopardy,' Pompeo said at the news conference.

Earlier this month, a senior US military official revealed that attacks by Iranian-backed groups on bases hosting US forces in Iraq were gathering pace and becoming more sophisticated.

The US has sent nearly 14,000 additional troops to the Middle East within the past six months in response to escalating tensions with Iran.

President Trump has not yet responded to Friday's attack, and Iraqi Security Forces are leading the response and investigation.

The Pentagon contractor who was killed has not yet been publicly named. All injured US troops are expected to make a full recovery.

US Defense Secretary Mark Esper, Secretary of State Mike Pompeo and Chairman of the Joint Chiefs of Staff Mark Milley are pictured at a press conference held at Mar-a-Lago in Palm Beach, Florida, Sunday

Since the weekend strikes, ties have been increasingly strained.

Iraq's government, acting in a caretaker capacity after Abdel Mahdi resigned in the face of street protests, threatened to summon the US ambassador.

'American forces acted on their political priorities, not those of Iraqis,' it said.

Dozens of lawmakers called on the government to review an agreement allowing the deployment of US soldiers in the country, saying the strikes amount to a violation of sovereignty that renders the pact obsolete.

The United States, meanwhile, accused Iraq of failing to 'protect' US interests in the country.

US defence officials have told AFP that pro-Iran factions now pose a greater threat than IS because of the repeated rocket attacks.

The US military has carried out 'defensive strikes' in Iraq and Syria against the Kataib Hezbollah militia group, the Pentagon said on Sunday, two days after an American civilian contractor was killed in a rocket attack on an Iraqi military base (file photo)

The Pentagon said it targeted three locations of the Iranian-backed Shi'ite Muslim militia group in Iraq and two in Syria (file photo)

Abdel Mahdi said he had been forewarned by Defence Secretary Mark Esper that the US would carry out the strikes.

'He told me the United States would strike the Hezbollah Brigades and I told him it would be a very dangerous act that could lead to an escalation,' Abdel Mahdi said.

The premier tendered his resignation in November after two months of anti-government rallies.

'This may well be the low point of US policy in Iraq,' said Iraq expert Fanar Haddad of Singapore University's Middle East Institute.

'That the national security adviser, MPs, a former minister and head of one of the most powerful parliamentary blocs are involved speaks volumes about the failure of US policy and the nature of the Iraqi state they helped create,' Haddad said.