U.S. army soldiers stand alongside their Iraqi counterparts as they provide security at a marketplace in Baghdad's Abu Ghraib, Iraq on April 29, 2009. (UPI photo/Ali Jasim) | License Photo

BAGHDAD, June 26 (UPI) -- Additional U.S. forces have arrived in Baghdad, bringing the total number of American service members in Iraq to 500, Pentagon officials said Thursday.

Pentagon spokesman Col. Steven Warren said, of the 500 American military personnel in Iraq, "Some of them are conducting an advise and assist mission, some are manning the joint operations center, some of them are part of the [Office of Security Cooperation] and yet others are Marines that are part of a [fleet anti-terrorism security team] platoon."


That number includes four more teams of U.S. military advisers that arrived in Iraq Wednesday evening. The military assessment teams are comprised of mostly Army Special Forces personnel and commanded by lieutenant colonels. These teams, Warren said, will fan out across Baghdad to assess the Iraqi security force's capabilities, advise and assist. They are expected to complete their reports within two to three weeks.

President Barack Obama authorized the deployment of up to 300 military advisers a week earlier in an effort to bolster the Iraqi government's response to a lightning offensive launched in early June by the Islamic State of Iraq and Syria (ISIS, also referred to as ISIL).

The U.S. military has also opened a joint operations center in Baghdad, as ordered by Obama "to share intelligence and coordinate planning to confront the terrorist threat of ISIL." A second joint operations center is expected to be established in northern Iraq, either in the coming days or weeks.