Calls for US troops to return to a combat role in Iraq are growing in Congress following the fall of Ramadi.

Witnesses testifying before the Senate Armed Services panel May 21 all agreed that the current strategy is failing and that the United States must work closely with Sunni fighters battling the self-proclaimed Islamic State (IS). They stopped short of endorsing a surge in combat troops — a nonstarter after the 2003 invasion — but argued for a boost in the number of US advisers and a substantial increase in their role.

"Without adequate force structure on the ground — and commitment — you cannot get out there and engage with the Sunni Arabs … They won't believe you're serious unless you put enough skin in the game," said retired Col. Derek Harvey, the director of the Global Initiative on Civil Society and Conflict at the University of South Florida. "And to do that we're going to need, in my judgment, about 15,000 or more" extra advisers on top of the 3,000 or so already there.

Lawmakers at the hearing appeared to agree that the United States is losing the fight against IS, but stopped short of endorsing the witnesses' recommendations.