-Afghan special-forces raid last month, both Pentagon and Afghan officials confirmed.
A statement by U.S. Forces, Afghanistan confirmed that Sheikh Abdul Hasib, described as the Emir of ISIS in the Khorasan Province (ISIS-K), was killed in the April 27 raid in southern Nangarhar province, eastern Afghanistan. Several high-ranking leaders of the group and 35 fighters were also killed, the US military said in a statement on Sunday.
General John W. Nicholson, commander of North Atlantic Treaty Organisation troops in Afghanistan, told reporters last month that USA and Afghan forces have been attacking Islamic State positions since early past year and had reduced its size by two-thirds.
While stationed in Nangarhar Province in the eastern part of Afghanistan, Abdul Hasib's group has been growing rapidly in numbers - as many as 3,000 at one stage - which resulted in Afghan and US forces combining to carry out a bombardment of airstrikes.
Two US army rangers also died in the raid, near an underground system of tunnels believed to be used by IS which were targeted by the largest conventional bomb ever used by the US. Two rangers, Sgt. Joshua Rodgers and Sgt. Cameron Thomas, were killed during the mission, possibly by friendly fire, Pentagon spokesperson Navy Capt. Jeff Davis told reporters at a briefing last month. The operation involved around 50 USA army rangers and dozens of Afghan troops. Even though Abdul Hasib was the primary target, various other ISIL leaders, as well as 35 ISIS militants, were eliminated during the raid.
He is credited with masterminding the Kabul hospital attack, although some Afghan security experts questioned whether a group still thought to be relatively small in Afghanistan could be capable of planning and carrying out such a large scale operation.
Hundreds of fighters had been killed or captured this year and the offensive was continuing, with over half the districts controlled by ISIS-K retaken, allowing residents in some places to return for the first time in two years.
North Atlantic Treaty Organisation commander in Afghanistan General John Nicholson confirmed Hasib's killing and warned that "any ISIS member that comes to Afghanistan will meet the same fate".
Next week, the Pentagon will ask the White House to send another 3,000 to 5,000 troops to Afghanistan to advise and train local military and police forces.
Islamic State has come under increased pressure after expanding its foothold in Afghanistan.