Trump warns Iran after Iraqi protesters storm US embassy in Baghdad

The US flew a rapid response team of Marines into Baghdad to reinforce its embassy after a mob of pro-Iranian demonstrators stormed the compound, setting fires and chanting "Death to America!"

Angered by US air strikes that killed two dozen fighters, hundreds of protesters spilled through checkpoints in the high-security Green Zone on Tuesday, demanding the ouster of US troops from Iraq and voicing loyalty to a powerful Iranian general, Qasem Soleimani of the Revolutionary Guard Corps.

US President Donald Trump blamed Tehran and warned that it would face punishment if Americans are killed.

"Iran will be held fully responsible for lives lost, or damage incurred, at any of our facilities," Trump said on Twitter late Tuesday.

"They will pay a very BIG PRICE! This is not a Warning, it is a Threat," wrote Trump, adding "Happy New Year!"

The message came at the end of a day in which Washington officials appeared surprised and furious over the ease at which the protestors entered the Green Zone, reaching the US embassy compound for the first time in years.

They carried flags of the hardline Kataeb Hezbollah (Hezbollah Brigades), a component of the Hashed al-Shaabi paramilitary network.

As live broadcasts showed the protestors battering down the high-security doors of the embassy reception building, smashing windows and burning a sentry box, the State Department and Pentagon demanded Iraq's leaders provide security to the compound -- which was already heavily fortified.

In phone calls with both Iraqi caretaker Prime Minister Adel Abdel Mahdi and President Barham Saleh, Secretary of State Mike Pompeo "made clear the United States will protect and defend its people, who are there to support a sovereign and independent Iraq," the State Department said.

Hours later a contingent of US Marines flew in from Kuwait, by which time some of the demonstrators had receded and others settled in for a sustained protest, preparing food for the evening.

Trump directly blamed Iran for "orchestrating an attack on the US Embassy in Iraq." "They will be held fully responsible," he said.

Tehran countered that the United States is itself to blame for air strikes that killed about two dozen Kataeb Hezbollah fighters on Sunday.

"The surprising audacity of American officials is so much that after killing at least 25... and violating the country's sovereignty and territorial integrity, that now... they attribute the Iraqi people's protest against their cruel acts to the Islamic Republic of Iran," said foreign ministry spokesman Abbas Mousavi.

The mob attack put a focus on the strains in the US-Iraqi relationship. Allies of Iran, which enjoys significant support in parts of the Iraqi government, increasingly challenge Washington's influence in the country.

US jet fighters on Sunday struck five Kateab Hezbollah outposts in Iraq and Syria after a series of rocket attacks on US-occupied facilities in Iraq over the past two months that are blamed on the group and its alleged Iranian sponsors.

One of those attacks, in Kirkuk on Friday, left an American civilian contractor dead and exhausted what US officials called Trump's "strategic patience" with Tehran.

"The president has shown a lot of restraint," Brian Hook, the State Department's Special Representative for Iran, told reporters Monday.

"We very much hoped that Iran would not miscalculate and confuse our restraint for weakness. But after so many attacks, it was important for the president to direct our armed forces to respond in a way that the Iranian regime will understand."

But it added to the growing calls by some political factions in Iraq to push US troops out of the country nearly 17 years after they entered and overthrew Saddam Hussein's regime.

Dozens of Iraqi lawmakers have called for a review of the agreement allowing about 5,200 US troops in Iraq, saying the airstrikes over the weekend violated the country's sovereignty.

An Iraqi government statement said the attacks "force Iraq to review its relations and its security, political and legal framework to protect its sovereignty".

The protesters who besieged the US embassy on Tuesday carried posters reading: "Parliament should oust US troops, or else we will!" Late Tuesday Kataeb Hezbollah hailed the protest outside as a "first lesson" to Washington, "so that Trump knows he did something extremely stupid".

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

But US officials said there were no plans to evacuate the mission, and no US personnel were reported injured. Ambassador Matthew Tueller, who had been on holiday leave, was on his way back to the embassy.

During the day Trump also called Abdel Madi to emphasise the need to protect US personnel and facilities in Iraq, the White House said.

He later tweeted his thanks to Abdel Mahdi and Saleh for "their rapid response upon request" to the embassy attack.