Transcript for U.S. Kills Al Qaeda's No. 2 Leader
We're going to turn to that major victory in the fight against Al Qaeda. The terror group's second highest ranking leader killed in a U.S. Air strike. He helped master mind the infamous underwear bomb and other plots to bring down American passenger jets. ABC's chief investigative correspondent Brian Ross on an obsession to bring an American jetliner down. Reporter: Demonstrations of what has long been the U.S. Nightmare scenario. A bomb hidden on an aircraft, something officials tonight hope they have made much less likely. With the announcement today that a cia drone had killed Nasir al-wuhayshi, regarded by us officials as the Al Qaeda figure most determined to attack the us. It was under al-wuhayshi that Al Qaeda tried to bring down a series of aircraft, with bombs hidden in shoes, underwear and printer cartridges. They all failed to detonate but what scared authorities was that each of the devices was able to get past what the U.S. Thought was state-of-the-art airport security. It's a significant development that he's dead. This is a blow to the Al Qaeda movement overall. Reporter: Al-wuhayshi, who rose from Osama bin laden's top aide to number two in Al Qaeda worldwide, was last seen in this 2014 video from Yemen rallying his fighters in a large open-air meeting, as if to defy the cia predator drones that flew overhead. And tonight there's word that a U.S. Drone strike in Libya targeted a second Al Qaeda terror leader, a man who killed dozens of hostages at a Libyan oil refinery in 2013, including three Americans. It's not certain tonight he was killed, but if so, it would be a week to remember for the cia, David. Two major developments. Brian, thank you.
This transcript has been automatically generated and may not be 100% accurate.