The unit, which goes by the unwieldy name Special Purpose Marine Air-Ground Task Force Crisis Response-Central Command, was created in Kuwait in 2013, less than a year after the Benghazi attack that claimed the lives of the U.S. ambassador to Libya, a member of his support staff and two CIA security contractors. A similar unit, based in Spain, was established to cover embassies in Africa.

U.S. Marines assigned to Special Purpose Marine Air-Ground Task Force-Crisis Response-Central Command prepare to deploy from Kuwait. | Sgt. David Bickel/U.S. Marine Corps

The self-contained units are on 24-hour standby and include air, ground, logistics and command elements. Beyond being able to reinforce embassy security, the units can use their aircraft to evacuate civilians, rescue downed aviators and come to the aid of countries struck by humanitarian or weather-related disasters.

In a series of Twitter posts on Tuesday afternoon, President Donald Trump alluded to the forces, while also threatening Iran and dismissing any comparison to Benghazi.

“The U.S. Embassy in Iraq is, & has been for hours, SAFE!“ he tweeted. “Many of our great Warfighters, together with the most lethal military equipment in the world, was immediately rushed to the site. Thank you to the President & Prime Minister of Iraq for their rapid response upon request....Iran will be held fully responsible for lives lost, or damage incurred, at any of our facilities. They will pay a very BIG PRICE! This is not a Warning, it is a Threat. Happy New Year!“

“The Anti-Bengahzi!“ he added, later correcting the spelling of the Libyan city.

In a statement on Tuesday night, Esper said Trump had also ordered Army reinforcements to the area.

“At the direction of the Commander in Chief, I have authorized the deployment of an infantry battalion from the Immediate Response Force (IRF) of the 82nd Airborne Division to the U.S. Central Command area of operations in response to recent events in Iraq,” he said. “Approximately 750 soldiers will deploy to the region immediately, and additional forces from the IRF are prepared to deploy over the next several days.“

The Marine deployment is no accident, a former senior administration official told POLITICO. Secretary of State Mike Pompeo, who was a heavy critic of the Obama administration’s handling of Benghazi and especially of his predecessor Clinton, has been concerned that a similar attack could bring the Trump administration its own version of the scandal.

“Pompeo has long dreaded having a Benghazi-type event on his watch and would be horrified if Americans died in a similar event, in part because of his criticism of Hillary Clinton during Benghazi,” said the former senior official, who spoke on condition of anonymity.

Not long after Esper made his announcement, U.S. Central Command distributed photos and video of the Marines packing up and getting ready to leave Kuwait in MV-22 Ospreys, a clear indication they were looking to send a message.

Sen. Lindsey Graham (R-S.C.) made the connection between Benghazi and Baghdad in a tweet after meeting with President Donald Trump on Tuesday. “President Trump is determined to protect American personnel and expects our Iraqi partners to step up to the plate. No more Benghazis,” Graham tweeted. “Very reassuring to see President Trump has beefed up our military capability to protect our personnel in Baghdad.”

Apache helicopters were spotted dropping flares over the embassy as the protests continued Tuesday, in what a U.S. official, who was not authorized to speak on the record, called a “show of force.”

No one inside the embassy has been hurt, the official said, nor has anyone been evacuated, although the ambassador was out of the country on holiday break at the time of the attacks.

Wesley Morgan reported from Washington and Daniel Lippman reported from Palm Beach, Fla.