The U.S. is adding 350 more troops to help protect the American Embassy in Baghdad and its support facilities in the capital, amid growing fears of an ISIS attack.

President Barack Obama approved the additional troops for protection of American personnel following a request by the State Department and a review and recommendation by the Defense Department, the White House said in a statement.

The buildup of U.S. troops in Baghdad follows the growing threat from Islamic State militants in northern Iraq. Earlier on Tuesday, ISIS had released a video showing the beheading of captured American journalist Steven Sotloff.

President Barack Obama waves as he boards Air Force One at Andrews Air Force Base on Tuesday, the same day that he authorized 350 more troops to be assigned to the U.S. Embassy in Baghdad

In the video entitled 'A Second Message to America,' Sotloff appears in a orange jumpsuit before he is beheaded by an Islamic State fighter.

The executioner – known as ‘Jihadi John’ - tells the camera: 'I’m back, Obama, and I’m back because of your arrogant foreign policy towards the Islamic State.'

Sotloff is the second American journalist to be killed by ISIS, and his death comes two weeks after James Foley was executed in a similar video.

Since early August the U.S. has carried out 114 airstrikes against the militants, the latest taking place near Mosul Dam on Monday.

In the video released of Sotloff's execution, 'Jihadi John' tells the camera that his death is due to 'your arrogant foreign policy towards the Islamic State

The decision raises the number of U.S. forces in the country to over 1,000.

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 U.S. 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.