WASHINGTON (Reuters) — The head of Islamic State in Afghanistan, Abu Sayed, was killed in a strike on the group’s headquarters in Kunar province earlier this week, the Pentagon said on Friday. Pentagon spokeswoman Dana White said in a statement that other members of the Islamic State group were also killed in the strike on Tuesday.

U.S. Defense Secretary Jim Mattis told reporters, "The significance is you kill a leader of one of these groups and it sets them back ... it is obviously a victory on our side in terms of setting them back, it is the right direction."

Sayed is the third Islamic State leader in Afghanistan to be killed since July 2016.

Former leader Abdul Hasib was killed in a joint U.S. and Afghan operation on April 27 in the eastern province of Nangarhar. Hasib’s predecessor Hafiz Saeed Khan died in a U.S. drone strike in 2016.

Afghan troops, backed by U.S. warplanes and special forces, have been battling militants linked to Islamic State in eastern Afghanistan for years. The deployment of the so-called Mother of All Bombs (MOAB) killed at least 95 fighters, according to the Afghan defence ministry, but fighting in the area has continued.

ISIL, sometimes known as Islamic State Khorasan (ISIS-K) after an old name for the region that includes Afghanistan, established a presence in Afghanistan in 2015 and overran large parts of Nangarhar and Kunar provinces, near the Pakistan border. However their part in the Afghan conflict had been largely overshadowed by the operations against the Taliban.