Pentagon Press Secretary Rear Adm. John Kirby said the 90 troops will join 40 other military personnel assigned to U.S. Embassy Baghdad as part of President Barack Obama's pledge to send up to 300 military advisers to provide assessments to the Iraqi government on how best to help bolster the Iraqi military.
Four more teams of 50 people each are expected to arrive in-country this week, Kirby added.
"We expect that they'll start to flow their assessments up through the chain of command in about two to three weeks."
The U.S. does not yet have a clear picture of the situation on the ground, and is utilizing U.S. military aircraft to conduct surveillance missions over Iraq, "sharing what we can with the Iraqi security forces."
U.S. forces in Iraq were given "acceptable assurances," Kirby noted, from the Iraqi government on Monday that the military would be afforded the same level of immunity granted to diplomats and U.S. forces assigned to the American embassy in Baghdad.