U.S. troops handover to the Iraqi military during a ceremony in Iraq
U.S. Army soldiers from the 3rd Brigade, 1st Cavalry Division, attend a casing of the colors ceremony as they withdraw from Camp Adder, now known as Imam Ali Air Base near Nasiriyah, Iraq, in 2011. Reuters/Mario Tama/Pool

U.S. soldiers could be deployed in combat roles within the Iraqi army as Pentagon officials weigh a number of options for containing the Islamic State group in Iraq. Embedding U.S. troops with the beleaguered Iraqi army, a move that could meet opposition among the American public and Congress, would see the U.S. put "boots on the ground" for the first time since the Iraq war officially ended in November 2011. It also would represent a significant policy shift for President Barack Obama, who was elected in 2008 promising to end both wars in the Middle East.

"There's always a look at doing more of what works well and doing less of what doesn't work well, and refining our efforts. That will continue," Pentagon spokesman Navy Capt. Jeff Davis told The Hill Monday. "You heard the secretary [Ashton Carter] allude to the one thing Friday, which is the fact that we're going to do more of these enabling missions and advise and assist and enabling missions outside the wire with trusted partners. Clearly there's desire to do whatever it takes to degrade and defeat ISIL," he added, using a different acronym for ISIS.

A second option sent to Pentagon leaders would embed U.S. forces with Iraqis closer to the battlefield, at the level of a brigade or a battalion, which is a gray area in terms of a return to combat. U.S. troops are currently working with Iraqis at the division level, which keeps them stationed at headquarters.

U.S. Military Deployments in Iraq | FindTheData

The U.S. and its coalition partners have been conducting airstrikes against ISIS in Iraq and Syria since August 2014, while providing training and advice to the Iraqi army and Syrian rebels. Those airstrikes and ground efforts by local forces have done little to regain the territory that the terror group had taken since it declared its caliphate in June 2014.

Rep. Jim McGovern, D-Mass., who opposed the Iraq War in 2002, said the Pentagon’s consideration of embedding U.S. troops with Iraqi forces was “extremely concerning.”

“We have been repeatedly reassured that the U.S. would not have a combat role in the war against ISIS, but this suggests just the opposite,” he said in an interview with the Hill. “This potential escalation is just the latest evidence that it is long past time for Congress to act. Our brave men and women in uniform are doing their duty.”

Last week, the Iraqi parliament granted the Russia permission to conduct airstrikes against ISIS inside Iraq, as it is doing in Syria already. It's not yet known when such strikes could begin.