Why U.S. forces remain in Iraq 20 years after 'shock and awe'

The roughly 2,500 U.S. troops are scattered around the country, largely in military installations in Baghdad and in the north.

Officials say the limited — but continued — troop level is critical as a show of commitment to the region and a hedge against Iranian influence.

Iran’s political influence and militia strength in Iraq and throughout the region has been a recurring security concern.

Defense Secretary Lloyd Austin says U.S. forces are ready to remain in Iraq, in a noncombat role.

By the time Washington withdrew its last combat troops in December 2011, tens of thousands of Iraqi civilians were dead, along with 4,487 American troops.

More than 3,500 troops were killed in hostile action and nearly 1,000 died in noncombat deaths.