By Missy Ryan
WASHINGTON, June 15 (Reuters) - The United States ordered military personnel to boost security for its diplomatic staff in Baghdad on Sunday and said some staff were being evacuated from the embassy as the Iraqi government battled to hold off insurgent forces.
"A small number of DOD (Department of Defense) personnel are augmenting State Department security assets in Baghdad to help ensure the safety of our facilities," Pentagon spokesman John Kirby said in a statement. It did not say how many military personnel had been deployed.
Separately, the State Department said it was evacuating some staff from the embassy and beefing up security there.
"Some additional U.S. government security personnel will be added to the staff in Baghdad; other staff will be temporarily relocated - both to our Consulate Generals in Basra and Arbil and to the Iraq Support Unit in Amman," the State Department said in a statement, without giving numbers.
The Baghdad embassy was reviewing staffing requirements but a "substantial majority" of the embassy presence in Iraq would remain in place, it said.
The Pentagon statement said that for the moment embassy staff would be evacuated using commercial, charter and State Department aircraft. But the U.S. military had airlift assets at the ready should they be needed.
The State Department also advised other U.S. citizens in Iraq to exercise caution and to limit travel to five provinces including restive Anbar in the west and Kirkuk in the north. U.S. citizens were also advised to register with a State Department program called Smart Traveler. The program enables U.S. embassies to stay in touch with citizens abroad in an emergency.
The U.S. government moves came as Iraqi government forces battled to hold off insurgents with the Islamic State in Iraq and the Levant, or ISIL, the Sunni militant group that has seized control of parts of northern Iraq.
HEAVILY FORTIFIED EMBASSY
The heavily fortified U.S. embassy occupies a sprawling swathe of land along the Tigris River in Baghdad, inside the secure Green Zone, where many Iraqi government buildings are located and which is off-limits to most Iraqis.
When the embassy opened in 2009, it had 1,200 employees, including diplomats, servicemen and women, and officials from 14 U.S. government agencies.
Dubbed the 'mega-bunker of Baghdad,' its size reflected the scale of the U.S. investment in Iraq following the 2003 invasion to oust Saddam Hussein, and an expectation the United States would have some sort of major long-term presence there.
The embassy's staff was later trimmed back in line with the U.S. military transition out of Iraq, which U.S. troops departed in late 2011.
U.S. officials have declined to say how many staff work there currently. But according to a 2013 State Department inspector general report, the embassy was moving to reduce its headcount from over 11,500 in January 2013 to 5,500 in January 2014.
In 2013, the United States also had diplomatic outposts in Arbil, Basra, and the contested city of Kirkuk.
Speaking to reporters last week, Pentagon spokesman John Kirby said that U.S. Central Command, which is responsible for Iraq, had "assets and resources" and existing plans should the United States need to evacuate personnel.
"But we're not there yet," he told reporters on Friday. He also said that any evacuation might not be carried out by the U.S. military.
President Barack Obama said on Friday he needed several days to determine how the United States would help Iraq deal with the stunning advance of the insurgents. But he ruled out sending U.S. troops back into combat in Iraq.
U.S. Defense Secretary Chuck Hagel ordered an aircraft carrier moved into the Gulf on Saturday, readying it in case Washington decides to pursue a military option. (Reporting by Jim Loney and Missy Ryan; Editing by Peter Cooney and Frances Kerry)