It was the second time in nine months that the leader of the Islamic State in the Khorasan, as the Afghanistan affiliate is known, was killed, Gen. John W. Nicholson, the commander of American forces in the country, said in the statement. Mr. Hasib’s predecessor, Hafiz Saeed Khan, was killed in July in a United States airstrike; he had been reported dead a few times before the American military confirmed it in August.
The United States military command in Afghanistan had said that an operation on April 27 targeted Mr. Hasib. Two American Army Rangers, Sgt. Joshua Rodgers and Sgt. Cameron Thomas, were killed in the operation, perhaps by so-called friendly fire, the Pentagon has said.
Afghan and American forces often go on joint missions. The one that killed Mr. Hasib included about 50 United States Army Rangers and a similar number of Afghan special security forces, the Pentagon has said. A firefight broke out during the raid, which lasted over three hours, and American F-16 fighter jets and Apache attack helicopters carried out airstrikes to protect the troops.
The Islamic State in the Khorasan, which uses an ancient name for the region that includes Afghanistan and Pakistan, expanded rapidly in the eastern part of Afghanistan, where government forces and an intense air campaign by the United States military have tried to rout the militants. They have been reduced to about 700 fighters, down from as many as 3,000, American officials said.
Last month, the United States dropped its largest conventional bomb, the 22,000-pound MOAB, on one of the group’s redoubts in Nangarhar, killing as many as 96 fighters, Afghan officials said.
Commanders decided on a ground assault, instead of another airstrike, to kill or capture Mr. Hasib because women and children were living in his compound, said an American military official who asked not to be identified when providing operational…