The U.S. embassy in Iraq was under siege by thousands of protesters -- many violent -- the demonstrators furious over the American air strikes over the weekend that targeted members of an Iraqi militia unit.
The militia is supported by Iran but is part of Iraq's armed forces.
The prime minister says the killing of at least 25 of its members was a serious breach of the country's sovereignty, but is also calling for calm.
American troops and some staff were still inside.
More troops and Iraqi special forces units trained by the Americans were deployed to secure the building.
Stun grenades used to keep people at bay.
The militia hit in the strikes is called Kataib Hezbollah, or "Battalions of the Party of God." It has links to both Iran's military and Lebanon's own Hezbollah.
Washington considers it a terrorist organization and it's long harassed U.S. forces.
Most recently the U.S. blames the group for a rocket attack at an Iraqi military base that killed an American contractor.
The air strikes were retaliation.
However, Kataib Hezbollah is part of a larger coalition of militias that -- although they have a separate command structure -- officially answer to Iraq government and often work jointly with its regular security forces.
These Iranian-backed militias also pull major political clout in Iraq.
Opposition to their influence is one of the reasons why Iraq has been swept by anti-government protests, in which hundreds have died.
But it's those same militias that organized this new protest at the embassy, although members say they didn't intend for violence.
U.S. President Donald Trump says that Tehran itself orchestrated both the protest and killing of the American contractor.
Tehran has said there is no evidence the militia was involved in the attack.