Al Qaeda leader Ayman al-Zawahiri was one of America's most wanted terrorists. CBS News senior investigative correspondent Catherine Herridge reports on the U.S. drone strike that took him out. Then former U.S. Secretary of Defense Chuck Hagel joined CBS News' Lana Zak to discuss the impact of the strike. CBS News Streaming Network is the premier 24/7 anchored streaming news service from CBS News and Stations, available free to everyone with access to the Internet. The CBS News Streaming Network is your destination for breaking news, live events and original reporting locally, nationally and around the globe. Launched in November 2014 as CBSN, the CBS News Streaming Network is available live in 91 countries and on 30 digital platforms and apps, as well as on CBSNews.com and Paramount+. Subscribe to the CBS News YouTube channel: https://youtube.com/cbsnews Watch CBS News: https://cbsn.ws/1PlLpZ7c Download the CBS News app: https://cbsn.ws/1Xb1WC8 Follow CBS News on Instagram: https://www.instagram.com/cbsnews/ Like CBS News on Facebook: https://facebook.com/cbsnews Follow CBS News on Twitter: https://twitter.com/cbsnews Subscribe to our newsletters: https://cbsn.ws/1RqHw7T Try Paramount+ free: https://bit.ly/2OiW1kZ For video licensing inquiries, contact: [email protected]