WASHINGTON _ Defense Secretary Ashton Carter said the Pentagon is sending more special operations troops to Iraq in an effort to break a military stalemate with Islamic State, although he stressed that Iraqi troops must conduct the ground fighting.
The "specialized expeditionary targeting force" will serve as advisers to the Iraqi military and Kurdish militias, and will help facilitate airstrikes by the U.S.-led coalition, Carter said Tuesday to the House Armed Services Committee.
"These special operators will over time be able to conduct raids, free hostages, gather intelligence and capture" Islamic State leaders, he said.
He did not say how large the force is, or where it will be based.
The Pentagon has deployed about 3,500 troops at six sites in Iraq over the last 16 months to help train and advise Iraqi security forces, while U.S. and allied aircraft bomb Islamic State positions on a daily basis.
The military also recently deployed fewer than 50 U.S. special operators to Kurdish-controlled northeast Syria to advise vetted Syrian and Kurdish rebel groups that are fighting Islamic State and its allies there.
"We're prepared to do more," Carter said Tuesday.
He said the expanded U.S. presence ultimately will allow for targeted raids and other operations in Syria, where Islamic State _ also known as ISIL _ is based.
"It puts everyone on notice in Syria: You don't know at night who's coming through the window," Carter said. "And that's the sensation we want all of ISIL's leadership and followers to have."
The White House has come under growing criticism since the Nov. 13 terrorist attacks in Paris for the continued impasse with Islamic State, with critics in both parties calling for a stronger U.S. response. The group continues to hold major cities in Sunni-dominated parts of Syria and Iraq.
But Carter's plan raises fresh questions about the U.S. military's expanding role in Iraq and Syria, and President Barack Obama's vow not to put American boots on the ground to fight the extremist group.
On Oct. 23, U.S. special operations forces and Kurdish fighters conducted an operation to free 70 prisoners held by Islamic State militants. The raid resulted in the first combat-related death of a U.S. service member in Iraq since 2011.
At the time, Carter characterized the rescue as part of the effort to train, advise and assist Iraqi forces, and not as a combat operation.
The new special operations force in Iraq marks a limited escalation for the White House, which has been wary of committing large numbers of ground troops to the Middle East.
Gen. Joseph Dunford, the nation's top uniformed officer who testified alongside Carter, said there could be more troops deployed _ beyond the 3,500 _ in the months ahead.
"I will not feel at all constrained in bringing forward recommendations for additional capabilities if that's what it takes to defeat the enemy," he said.