Protesters burn property in front of the US embassy compound, in Baghdad, December 31, 2019. (Photo: Reuters)

The protests posed a new foreign policy challenge for US President Donald Trump, who faces re-election in 2020. He threatened to retaliate against Iran, but said later he does not want to go to war.

The State Department said diplomatic personnel inside were safe and there were no plans to evacuate them. Embassy guards used stun grenades and tear gas to repel protesters, who stormed and burned the security post at the entrance but did not breach the main compound.

The Pentagon said that in addition to Marines sent to protect embassy personnel, about 750 soldiers were being sent to the Middle East and that additional troops were prepared to deploy over the next several days. More than 5,000 US troops are stationed in Iraq supporting local forces.

The protests followed US air strikes on Sunday on bases operated by the Iranian-backed militia Kataib Hezbollah inside Iraq, which killed at least 25 fighters and wounded 55. The strikes were retaliation for the killing of a US civilian contractor in a rocket attack on an Iraqi military base, which Washington blamed on Kataib Hezbollah.