The violence comes as Iran and its allies have faced unprecedented mass protests in recent months and after heavy US sanctions on Iran that have cratered its economy and raised tensions across the region. In Iraq, the protesters have been angered at their own government’s corruption and economic mismanagement, as well as its close ties to Tehran.
President Donald Trump blamed Iran for the attack on the embassy and Defence Secretary Mark Esper later announced the immediate deployment of an infantry battalion of about 750 soldiers from the Army’s 82nd Airborne Division to the Middle East. He did not specify their destination, but a US official familiar with the decision said they would go to Kuwait.
Iran has denied any involvement in the attack on the embassy. Foreign Ministry spokesman Abbas Mousavi was quoted by state media on Tuesday as warning the US against any “miscalculation” in the worsening standoff.
Iran’s supreme leader, Ayatollah Ali Khamenei, criticised the US airstrikes and in remarks carried by the semi-official ISNA news agency, he accused the US of taking revenge on Iran for the defeat of the Islamic State group, which he said was an American creation.
In an apparent reference to Trump’s allegations of Iranian involvement, Khamenei said that “if the Islamic Republic makes a decision to confront any country, it will do it directly”.
The US and Iran have vied for influence over Iraq since the 2003 US-led invasion that toppled Saddam Hussein. Iran has close ties to Iraq’s Shiite majority and many of its major political factions, and its influence has steadily grown since then.
Iran helped to mobilise tens of thousands of mostly Shiite militiamen to battle the Islamic State group when it stormed across northern and western Iraq in 2014 as the armed forces collapsed. In the subsequent campaign against the extremists, the US and Iran both provided vital aid to Iraqi forces, who eventually declared victory in December 2017.
The political influence of the Iran-backed militias, known as the Popular Mobilisation Forces, has risen in recent years, and their allies dominate the parliament and the government. That has made them the target of mass protests since October that are unrelated to the attack on the embassy.
For weeks, the anti-government protesters have been trying to enter the Green Zone housing the government and the US Embassy, but have been beaten back by security forces, who have killed hundreds of demonstrators.
The militiamen and their supporters, however, were able to quickly enter the Green Zone and mass in front of the embassy, with little if any resistance from authorities.
By Wednesday morning, they had set up a small sit-in of their own, with about 50 tents set up between two main gates about 500 meters (yards) apart.
Demonstrators could be seen hurling rocks over the walls of the embassy compound, where U.S. troops responded by firing tear gas from the roofs of buildings. Iraqi security forces deployed nearby watched the standoff unfold without intervening.