Shortly after the fall of Iraq’s second-largest city, Mosul, to the Islamic State in June 2014, a delegation of senior officials from Iraqi Kurdistan visited Washington with a troubling question: From where, they asked, would the force come to retake the city? The Iraqi army was too shattered, and the Kurds were too weak, and outside powers such as Turkey and the United States were unwilling to commit ground forces.

A lot has happened in the nearly two years since then. Among other things, the Obama administration has retrained nearly 20,000 Iraqi troops, dispatched some 5,000 U.S. trainers, Marines and special operations forces to the area, and launched more than 11,000 combat air sorties against Islamic State targets. Yet when another senior Kurdish delegation circulated through Washington last week, their question about Mosul was unchanged: Who is going to do this?

“We heard a plan is close to being drawn up” for retaking the city, said Qubad Talabani, deputy prime minister of the Kurdish Regional Government in Iraq, who recently met in Baghdad with Prime Minister Haider al-Abadi and the senior U.S. commander in the theater, Lt. Gen. Sean MacFarland. “But we got a sense there are gaping holes in that plan.”