Hezbollah, the Lebanese militant group, named Naim Qassem, its longtime deputy leader, as its new secretary-general on Tuesday, replacing Hassan Nasrallah, who was assassinated in Israeli airstrikes south of Beirut last month.

The naming of Qassem, who is around 70 years old, came amid Hezbollah’s deadliest war with Israel since the group was founded in the 1980s. In recent months, Israel has killed large numbers of Hezbollah leaders and commanders, including both Nasrallah and his presumed successor, Hashem Safieddine, as well as many of the group’s rank-and-file fighters.

A Hezbollah statement said Qassem had been chosen by the group’s Shura Council, a senior leadership body, "in adherence to the principles and goals of Hezbollah.” It did not say how many members took part in the process or whether there had been any other contenders.