An additional four team of United States military advisers were deployed in Iraq.

An additional four teams of U.S. advisers arrived in the Iraqi capital last night, Pentagon spokesman Army Col. Steve Warren said, bringing the number of teams to six.

Warren described the deployments as enhanced teams commanded by lieutenant colonels that are fanning out across Baghdad and assessing the Iraqi military. President Barack Obama ordered the teams to Iraq following gains made by Syrian-based Sunni militants of the Islamic State of Iraq and the Levant who have overrun towns and cities across Iraq’s northern and western provinces as they move closer to Baghdad, facing little or no resistance from Iraqi security forces.

The four teams bring 50 people with them, which puts the number of American assessors on the ground to 90. Warren said an additional 90 personnel have set up the joint operations center in Baghdad, meaning 180 of the possible 300 U.S. service members Obama said he is prepared to send to Iraq have arrived.

Overall, there are approximately 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,” Warren said.

The assessment teams are mostly made up of Army Special Forces personnel. They will advise and assist the Iraqi military at various levels of command.

The teams will take two to three weeks to assess the Iraqi military and make their reports, officials said.