U.S President Donald Trump has issued a threat to Iran, after blaming the nation for an attack on the US embassy in neighbouring Iraq.
The American compound was attacked by a crowd of angry demonstrators furious over the deaths of militia members killed by US air strikes.
President Trump tweeted on New Year’s Eve that Iran “will pay a very big price” for any damage or loss of life.
“This is not a warning, it is a threat,” he said.
US defence secretary Mark Esper later announced that about 750 soldiers would immediately be deployed to the region.
“The United States will protect our people and interests anywhere they are found around the world,” he wrote in a tweet.
The angry crowd set a guard post in the street on fire and breached a reception area in the compound, forcing US troops to fire teargas on the protesters.
Iran, meanwhile, denied Mr Trump’s accusation that it had somehow orchestrated the incident, condemning the “audacity” of the claim.
The militia targeted by the US air strikes was an Iranian-backed force, the Kataib Hezbollah militia in western Iraq and eastern Syria.
At least 25 fighters died in the US bombing of their bases on Sunday, which Washington said was a retaliation for the death of an American civilian worker killed during a rocket attack on an Iraqi military base.
Iraqi Prime Minister Adel Abdul Mahdi said the strikes had violated his country’s sovereignty. The leader of the Kataib Hezbollah militia, Abu Mahdi al-Muhandis, warned that its response “would be very tough on the American forces in Iraq”.
Mr Trump has said he expects Iraqi forces to protect the embassy and its staff, and thanked Prime Minister Mahdi for the action already taken during the attack.
Fifty people were treated for tear-gas inhalation at hospitals in Baghdad, a health ministry source told reporters.
None of the embassy staff were evacuated, but they are now on lockdown, CBS reported. Ambassador Matthew Tueller was outside Iraq for a previously scheduled holiday and was reportedly returning to the embassy.
Hours after the protest began, Prime Minister Abdul Mahdi called on people to leave the area around the US embassy.
“Any attack on or harassment of embassies and foreign delegations are acts that will be firmly prevented by security forces and severely punished by the law,” he said.