U.S. Special Operations forces believe they killed ISIS’ “second in command” in an operation inside Syria, according to a senior defense official.

Haji Imam, whose real name is said to be Abd ar-Rahman Mustafa al-Qaduli, is a senior religious leader of the self-proclaimed Islamic State and had been considered to be next in line to succeed “caliph” Omar al-Baghdadi, though some ISIS watchers say his Turkoman background ruled that out.

The official says U.S. forces killed a high-ranking official—who they believe to be Haji Imam—in a raid on his vehicle, after they tracked him for several days.

Defense Secretary Ash Carter and Chairman of the Joint Chiefs of Staff Marine Gen. Joseph Dunford will announce the operation this morning at the Pentagon.

Carter will also confirm the reported killing of ISIS’s “minister of war” in a strike this month. Tarkhan Batirashvili, better known as Omar al-Shishani or “Omar the Chechen,” was reported to be badly wounded by an airstrike, according to the Syrian Observatory for Human Rights.

That makes two major hits by the U.S. special operators inside Syria, and a fiery coalition riposte to the ISIS-claimed attacks in Belgium on Tuesday that claimed the lives of 31 people, including two Americans. Arrests continued across Belgium and also in France in the wake of the attacks, unearthing a network of European citizens who are part of what Belgian officials say is a wider network than they originally believed was linked to the Paris attacks of last November that claimed 130 lives.

Around 50 special operators from the Joint Special Operations Command are operating throughout northern Syria, helping guide local forces’ military movements, teaching them how to share intelligence, and call in airstrikes that have become increasingly more effective, and also carrying out a number of their own mostly undisclosed operations to degrade the ISIS network, U.S. military officials said, speaking anonymously because they were not authorized to describe the actions publicly.

A Pentagon spokesman reached Friday morning declined to comment.

— Kimberly Dozier