Al-Qaeda's leader appeared in a video online Friday, calling on Muslims to fight back days before the 15th anniversary of the Sept. 11, 2001 terror attacks that killed nearly 3,000 people.
"We mark in these days the passage of nearly 15 years since the blessed invasions in Washington, New York and Pennsylvania," Ayman al-Zawahiri said in the video, according to SITE Intelligence Group.
Zawahiri, a former surgeon, was the second in command to Osama bin Laden when al-Qaeda terrorists hijacked planes and crashed them into the World Trade Center in N.Y., the Pentagon building in D.C., and a field in Shanksville, Pa., fifteen years ago.
The 20-minute video address by Zawahiri focused on al-Qaeda's reasons behind the 9/11 attacks and its impact on the U.S., and urged his followers to focus on targeting the U.S. and its allies, while bringing the battle to their own soil, according to a translation by the Middle East Media Research Institute.
Zawahiri, 65, also appealed to non-Muslim African-Americans and called on them to convert to Islam.
The video is part of al-Qaeda's recent plan to stay relevant while rival terrorist group the Islamic State draws more attention across the world and many more recruits, former White House counterterrorism adviser Richard Clarke told ABC News.
Unlike bin Laden, who was killed in 2011 by U.S. special forces, Zawahiri has evaded capture for over a decade. He is believed to be in Pakistan or Afghanistan.