BAGHDAD • The US embassy siege by pro-Iran protesters in Baghdad lasted just over a day, but analysts warn it could have lasting implications for Iraq's complex security sector and diplomatic ties.
Baghdad has been struggling to keep up its precarious balancing act between its allies Teheran and Washington as tensions spiral following the US withdrawal from the 2015 nuclear pact with Iran.
The regional rivalry is partly playing out among Iraq's security forces: the Americans have trained Iraq's army units and elite troops, while Iran has assisted the Hashed al-Shaabi force.
On Tuesday, hundreds of Hashed supporters stormed the high-security Green Zone and besieged the US embassy. The ease with which they breezed past US-trained forces demonstrated the Hashed's dominance in Iraq, said Dr Harith Hasan, an expert at the Carnegie Middle East Centre.
"A political military faction imposed its will on everyone and commandeered all decisions," Dr Hasan wrote. As a result, he predicted, "this new year will be the beginning of Iraq's lean years, leading to its isolation".
Founded in 2014, the Hashed is formally part of Iraq's government forces and its nominal head, Mr Faleh al-Fayyadh, also serves as the country's national security adviser.
But the US fears the network's Shi'ite-majority units - many of which fought American troops after the US-led invasion in 2003 - are being used to exert Iran's clout.
Those tensions boiled over last week when a US contractor working in Iraq was killed in a rocket attack blamed on Kataeb Hizbollah, a hardline, pro-Iran Hashed faction.
It was the latest in a string of attacks on American troops and the embassy in Iraq that the US has blamed on groups loyal to Teheran.
A senior American defence official told AFP the US was frustrated that Iraqi troops were either "unable or unwilling" to put a stop to the rocket attacks.
"We are concerned the Iraqi security infrastructure is compromised," the official said. "There is what we believe to be a Hashed overmatch of Iraqi security forces. So sometimes our Iraqi partners say, what can we do?" he added.
Both US and Iraqi officials said they were especially alarmed to see Hashed units being deployed in recent weeks inside the Green Zone, home to government buildings, United Nations offices and key foreign embassies.
The clearest sign of the Hashed's effective control of the zone came during the embassy attack, when its backers breezed past US-trained units to reach the embassy.
An Iraqi special forces fighter guarding the Green Zone said he had to let the Hashed supporters through as he had no orders to intervene. He said: "Our hands are tied. The Hashed is now the most influential of Iraq's forces because the military and political leaders are allowing it to play this role."
Among those marching in on Tuesday were top figures in Iraq's security apparatus: Mr Fayyadh, his deputy Abu Mahdi al-Muhandis, and Hashed commanders Qais al-Khazaali and Hadi al-Ameri.
Their presence outraged US Secretary of State Mike Pompeo, who tweeted photographs of the four and slammed them as "terrorists" and "Iranian proxies".
It marked a major shift in the US position towards, specifically, Mr Fayyadh and Mr Ameri - whom the US ambassador had been meeting in recent months.
"All of this demonstrates how much hold Teheran has over Baghdad. There shouldn't be any illusion," said Mr Phillip Smyth, a US-based specialist in Shi'ite armed groups.
The attack could even have repercussions on Iraq's diplomatic standing, officials and analysts said.
Already, the US has declined to invite Iraqi Prime Minister Adel Abdel Mahdi to Washington because American officials saw him as "too close" to Iran.
The US has also blacklisted a host of Iraqi political figures, Hashed units and even banks in recent months and has suggested dozens more could be sanctioned.
"Iraq is at risk of becoming a pariah state, isolated from the rest of the world like Venezuela, North Korea and so on," said a senior Iraqi diplomat.