President Barack Obama on Tuesday ordered about 350 more US troops to Baghdad to protect American diplomatic facilities and staff in the Iraqi capital, the White House said.

The announcement came hours after the so-called Islamic State (also known as ISIL) released another video showing a masked terrorist with a British accent beheading a US journalist.

The footage released Tuesday purports to show the execution of Steven Sotloff at the hands of an IS member. In the same video, the radical Islamist group threatened to execute British national David Cawthorne Haines next unless its demands were met.

The murder of Sotloff came a few weeks after US journalist James Foley was executed in the same manner.

The Sunni extremist group has declared an Islamic “caliphate” in regions under its control in Iraq and Syria, after it swept through much of the Sunni Arab heartland north of Baghdad and then stormed minority Christian and Yazidi areas since June.

File photo dated June 02, 2011 courtesy Etienne de Malglaive shows American journalist Steven Sotloff (center with dark helmet) talking to Libyan rebels on Al Dafniya front line, 25 km west of Misrata. (Photo credit:AFP PHOTO HANDOUT- © ETIENNE DE MALGLAIVE)

File photo dated June 02, 2011 courtesy Etienne de Malglaive shows American journalist Steven Sotloff (center with dark helmet) talking to Libyan rebels on Al Dafniya front line, 25 km west of Misrata. (Photo credit:AFP PHOTO HANDOUT- © ETIENNE DE MALGLAIVE)

The US has been carrying out airstrikes on IS positions in Iraq and already has hundreds of personnel shoring up diplomatic security in Iraq.

“The president authorized the Department of Defense to fulfill a Department of State request for approximately 350 additional US military personnel to protect our diplomatic facilities and personnel in Baghdad, Iraq,” a White House statement said.

“We will (also) continue to support the government of Iraq’s efforts to counter ISIL, which poses a threat not only to Iraq, but to the broader Middle East and US personnel and interests in the region.”

Obama, on his way to Estonia and a NATO summit in Wales, “will be consulting this week with NATO allies regarding additional actions to take against ISIL and to develop a broad-based international coalition to implement a comprehensive strategy to protect our people and to support our partners in the fight against ISIL,” it said.

The buildup of US troops in Baghdad follows the growing threat from Islamic State militants in northern Iraq. Since early August the US has carried out 124 airstrikes against the militants, the latest taking place near Mosul Dam on Monday.

The additional troops will not serve in a combat role, the White House said. Most are from the Army and some are Marines, the Pentagon said in a statement.

Approximately 820 troops have now been assigned to augment diplomatic security in Iraq, said Rear Adm. John Kirby, the Pentagon’s spokesman.

The additional troops will come from within the US Central Command area of operations and will include a headquarters element, medical personnel, associated helicopters and an air liaison team, Kirby said. Fifty-five troops in Baghdad since June will be redeployed outside of Iraq and replaced by 405 newly deployed troops, he said.