and the plotters of the attack included osama bin laden, shaik mohammed and ayman al-zawahiri. america swore revenge and over the next 20 years america killed bin laden, captured shaik mohammed, invaded afghanistan and iraq, bombed pakistan, syria, yemen, somalia, and libya. deployed troops to mali, kenya, and nigeria, and completely obliterated the big shampoo bottle industries. only tiny bottles for you! ( laughter ) but in that whole time, the u.s. never managed to find ayman al-zawahiri. until yesterday. >> the u.s. has now killed the world's top terror target measure 20 years after 9/11, the hunt for bin laden's number two is now over. >> he has been in hiding for more than 20 years, one of the world's most-wanted terrorists. but tonight, the united states finally caught up with ayman al-zawahiri. >> justice has been delivered, and this terrorist leader is no more. >> senior officials say the u.s. government used an unmanned drone and hellfire missiles to target the third-floor balcony of a residential apartment building in downtown kabul. >> experts say hellfire missiles