Nasser al-Wuhayshi, head of Al Qaeda in the Arabian Peninsula, vowed to fight on in an Internet statement.
"You have to fight one generation after the other, until your life is ruined, your days are disturbed and you face disgrace. The fight between us and you was not led by Usama alone," Wuhayshi said, according to Reuters.
Wuyashi, who is also a top terror target, was a close aide to bin Laden in Afghanistan in the 1990s.
"What is coming is greater and worse, and what you will be facing is more intense and harmful," he said in a eulogy to bin Laden, according to Reuters.
The Yemen-based terror organization claimed responsibility for the attempted 2009 bombing of a passenger jet over the U.S. on Christmas Day. It was also blamed for bombs that were found in mail packages en route to the U.S. last year.