President Barack Obama has approved sending up to 1500 additional troops to Iraq to aid the Baghdad government and Kurdish forces fighting the Islamic State group, roughly doubling the number of US troops in the country.
The 1500 will include a group of advisers to help Iraqi forces plan operations and a group of trainers who will be deployed across the country.
Some of the advisers will be deployed to western Anbar province, where the Iraqi army has been forced to retreat from advancing IS jihadists, a defence official said.
Defence secretary Chuck Hagel recommended the move to Obama based on a request from the Iraqi government and the assessment of US Central Command, which is overseeing the air war against the IS militants, the Pentagon said.
The deployment coincides "with the development of a coalition campaign plan to defend key areas and go on the offensive" against IS fighters who have grabbed large areas of Iraq and neighbouring Syria, it said.
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The training sites will be located in northern, western, and southern Iraq and "coalition partners will join US personnel at these locations to help build Iraqi capacity and capability," it added.
There are now about 1400 American troops in Iraq, including 600 advisers in Baghdad and Arbil, and 800 troops providing security for the US embassy in the capital and the Baghdad airport.
Obama had previously authorised up to 1600 troops. His decision Friday will raise the maximum troop footprint to 3100.
The US president had resisted keeping troops in Iraq earlier in his term, vowing to end the American presence that began with the 2003 invasion and continued as an occupation through 2011.
US officials had discussed the possibility of keeping several thousand troops in Iraq after 2011, but talks with the Iraqi government, then led by prime minister Nuri al-Maliki, broke down over the issue of legal immunity, which Washington insisted on and Baghdad declined to provide.
With Friday's announcement, Obama will be deploying a force to Iraq along the lines of that considered in 2011, under legal protections similar to those it rejected as insufficient three years ago.
