BEIRUT (AP) — Sheikh Naim Kassem has been acting head of Hezbollah since then their long-time leader Hassan Nasrallah was killed as part of an Israeli offensive that killed many senior officials in the Lebanese militant group.

Kassem gave a defiant televised speech On Tuesday, he claimed the group’s military capabilities were intact and Israelis would only suffer more if fighting continued.

Like Nasrallah, Kassem is one of the founding members of the Shiite political party and armed group, but is widely believed to lack the charisma and oratorical skills of the former leader.

Nevertheless, it was often the clergyman with the white turban and the gray beard public face of the group. After Nasrallah went underground for fear of being assassinated by Israel, appearing only in televised speeches, Kassem continued to show up and sit in at rallies and ceremonies Interviews with foreign journalists.

Mohanad Hage Ali, a senior researcher at the Carnegie Middle East Center think tank who studies Hezbollah, said that at least in his public statements, Kassem was perceived by many as more “extreme” than Nasrallah.

In practice, however, his power within the group was limited under Nasrallah. Hashem Safieddine, a cousin of Nasrallah who oversees the group’s political affairs – not Kassem – was widely seen as the leader’s heir apparent. However, no announcement has been made and Safieddine has not appeared publicly or made any public statements since Nasrallah’s death.

Kassem has been sanctioned by the United States, which considers Hezbollah a terrorist group.

He was born in the city of Kfar Fila in southern Lebanon and studied chemistry at the Lebanese University before working as a chemistry teacher for several years.

At the same time, he pursued religious studies and participated in the founding of the Lebanese Union for Muslim Students, an organization that aimed to promote religious affiliation among students.

In the 1970s, Kassem joined the Movement of the Dispossessed, a political organization founded by Imam Moussa Sadr that advocated for greater representation of Lebanon’s historically overlooked and impoverished Shiite community. The group morphed into the Amal Movement, one of the main armed groups in the Lebanese civil war and now a powerful political party.

He then joined the nascent Hezbollah, which was founded with support from Iran after Israel invaded Lebanon in 1982 and occupied the country’s southern region.

From 1991 he served as the group’s deputy secretary general, initially under Nasrallah’s predecessor Abbas Mousawi, who was killed in an Israeli helicopter attack in 1992.