With the addition on new troops, the number of US troops in the country would increase from 3,870 to 4,087, the Pentagon said.
This does not include temporary troops. The announcement was made by the US Defense Secretary Ashton Carter during an unannounced visit to Iraq.
White House Press Secretary Josh Earnest told reporters that the President's instructions to his national security team have consistently been to look for opportunities to reinforce those elements of US campaign that are showing some progress.
"Iraq is a sovereign nation, and making decisions like retaking Mosul from ISIL (Islamic State) will be decisions that are made by the Iraqi government," he said.
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"What the US has sought to do at every turn is to support our partners in Iraq as they implement a political strategy to unite the country, but also as they carry out a military strategy to drive ISIL out of those areas of Iraq where they have encroached," Earnest said.
"While the deployment of an additional 217 US troops to fight ISIL is welcome, this is yet another example of the kind of grudging incrementalism that rarely wins wars, but could certainly lose one," he said.
"This deployment is also representative of the increasing operational demands imposed upon our military that are not funded in the President's already inadequate defense budget request. Continuing to ask our military to do more with less is irresponsible and is placing the lives of our service members at increased risk," McCain said.