WASHINGTON — The Pentagon on Tuesday sent some 100 Marines to the U.S. Embassy in Baghdad to bolster security after Iraqi Shiite protesters enraged by American airstrikes on Iran-backed militia in Iraq and Syria breached the compound, U.S. officials said.

Defense Secretary Mark Esper said in a statement issued earlier Tuesday that the new forces would help “ensure the security of our embassy and personnel working in Baghdad.” Esper’s statement came as television footage showed dozens of the protesters standing along the walls of the embassy compound and occasionally throwing rocks.

Many people in the crowd were waiving the yellow flags of the Iran-backed Shia militias, known as Popular Mobilization Forces. Some fighters in that force helped battle the Islamic State under the Iraqi security forces umbrella, however the United States has blamed the group for recent rocket attacks on American positions in the country, including an attack Friday on a base in northern Iraq's Kirkuk that left a U.S. contractor dead and injured four American service members.

A U.S. official said infantry from 2nd Battalion, 7th Marines were shuttled early Tuesday afternoon from Kuwait to the embassy in Baghdad. The Marines were in Kuwait assigned the Corps’ crisis response team for the U.S. Central Command area. The unit is specially trained to quickly respond to issues that arise within that region, which includes the Middle East and Afghanistan.

Pentagon imagery released Tuesday shows the Marines loading their rifles and loading up to move into Iraq via MV-22 Osprey tilt-rotor aircraft.

The troop influx came following a “show of force” conducted by two AH-64 Apache attack helicopters, said the official who spoke on the condition of anonymity to discuss the ongoing situation. The official said Apaches would remain available to help secure the embassy as long as they were needed and more troops had been ordered to prepare to deploy should they be needed. However, the official would not reveal how many troops in total were now at the embassy.

The official said Iraqi security forces had helped control the situation, which had not resulted in any deaths as of Tuesday afternoon.

“As in all countries, we rely on host nation forces to assist in the protection of our personnel in country, and we call on the government of Iraq to fulfill its international responsibilities to do so,” Esper said in a statement. “The United States continues to support the Iraqi people and a free, sovereign, and prosperous Iraq."

A second U.S. official said the embassy’s main building had not been breached and the protest – consisting mostly of PMF militia – appeared to be “calming somewhat.” The official, who also spoke of the condition of anonymity, said the United States as of Tuesday did not plan to evacuate the embassy.

However, media reports from Iraq indicated at least some of the militia had set up camps just outside the embassy grounds. The Associated Press reported the protesters “intended to stage a sit-in.”

The protests came one day after PMF groups vowed retaliation following the U.S. airstrikes Sunday on five locations in Iraq and Syria housing Iranian-backed Kataeb Hezbollah militia, which U.S. officials blamed for the deadly attack at Kirkuk and nearly a dozen similar attacks on bases housing American and anti-ISIS coalition forces in Iraq. The strikes Sunday killed at least 25 militiamen, the AP reported.

Brian Hook, the State Department’s special representative for Iran, on Monday labeled Kataeb Hezbollah a “rogue militia” closely tied with Iran’s elite Quds Force, which conducts most of Iran's military operations outside its borders.

“They are not acting in the interests of the Iraqi people,” Hook said of the militia. “They are violating Iraq’s sovereignty.”

Hook said Monday – before the protests began – that the killing of an American spurred President Donald Trump to approve the airstrikes as a deterrent to any further Iranian aggression in the region following non-lethal responses to other recent acts by Iran. Those acts include attacks on commercial ships, the downing of an American drone in the Persian Gulf in June, and a September drone and cruise missile strike on critical Saudi Arabian oil infrastructure.

The United States has moved some 14,000 troops into the Middle East since May citing Iranian aggression. Those troops largely consist of a Navy carrier strike group, bomber and fighter jet personnel, air and missile defense soldiers and units sent to bolster force protection. Most of the ground troops were sent to Saudi Arabia, defense officials have said.

“We’ve also made clear for some time that we’re not going to tolerate these kinds of attacks,” Hook said. “The president has shown a lot of restraint. … I think Iran would like to bait the president into all sorts of things, but the president has shown, I think, very skillful leadership navigating through this, using our diplomacy backed up by hard power.”

In a tweet on Tuesday, Trump blamed Iran for the uprising at the American embassy and called on Iraqis to denounce Iranian influence in their country.

“To those many millions of people in Iraq who want freedom and who don’t want to be dominated and controlled by Iran, this is your time!” Trump tweeted.

The United States has about 5,200 troops in Iraq. In a statement, Iraqi Prime Minister Adel Abdul-Mahdi said the U.S. strikes on Sunday were a “flagrant violation” of his country’s sovereignty and vowed to evaluate Iraq’s relationship with the American troops in its country, where U.S. and allied troops have led the ISIS fight since 2014.

dickstein.corey@stripes.com

Twitter: @CDicksteinDC

