The US is to send up to 450 military advisers to Iraq to help train local forces fighting Islamic State, the White House says.
President Obama made the decision following a request from Iraqi Prime Minister Haider Al-Abadi, it said.
The troops will be deployed to the Taqaddum military base in Anbar province. IS seized Ramadi – the capital of Anbar – in May.
It has made gains across the region despite US-led coalition air strikes.
The move is aimed at enabling more Iraqis – mostly Sunni tribal volunteers – to integrate into the Iraq army and reclaim territory from Islamic State.
“These new advisers will work to build capacity of Iraqi forces, including local tribal fighters, to improve their ability to plan, lead, and conduct operations” against IS in Anbar, the White House statement added.
Islamic State took control of Iraq’s second city Mosul a year ago. It has also captured the Syrian town of Tadmur and the neighbouring ancient ruins of Palmyra.
The deployment of military advisers to Taqaddum brings the number of US training camps in Iraq to five.
Some 9,000 Iraqi troops have already been trained at Al-Asad, Besmaya, Irbil, and Taji, the White House said.
President Obama continues to resist demands for combat troops.
Analysis – Jon Sopel, BBC North America editor
After the fall of Ramadi and then the suggestion by the US defence secretary that the Iraqis didn’t have the will to fight, this announcement is an admission that the strategy isn’t working.
What is striking is that these additional troops will be operating from a military base in Anbar province, where Islamic State has made major gains.
The aim is to bring Sunni tribes into the fight against IS – they have so far refused to get involved out of their mistrust of the Shia dominated government in Baghdad.
Involving them is now a key component of Pentagon strategy.
But it will mean the US trainers will be operating close to IS front lines, and that will present its own security concerns for the US, and an opportunity for Islamic State.
The decision to send more military advisors follows months of behind-the-scenes debate within the White House on how to retake Mosul and Ramadi, the New York Times reports.
US officials believe a major factor in the fall of Ramadi was a lack of training of Iraqi forces.
However, former Iraqi national security adviser, Mowaffak al-Rubaie, told the BBC the new plans were not enough.
“This is too little too late. I call for the American administration to get their act together.” he added.
“They don’t have any unified strategy. We don’t understand their policy in Iraq and in Syria, in the region. They are giving conflicting signs.”
The added personnel would bring the total of US military personnel, including trainers and advisers, in Iraq to 3,550 troops. The UK is sending an extra 125 troops to 275.
It also emerged on Wednesday that an American fighting with Kurdish forces was killed in Syria a week ago. Keith Broomfield was from Massachusetts.