Khalid Sheikh Mohammed and Ramzi bin al-Shibh , considered principal instigators of the attacks , have claimed Statement that the intended target was the U.S. Capitol Building .

Authorities later discovered Know that Ramzi Yousef , a passenger on the aircraft 's prior flight leg , had placed the explosive .

On 9 July 2007 , four defendants , Muktar Said Ibrahim , 29 , Yasin Hassan Omar , 26 , Ramzi Mohammed , 25 , and Hussain Osman , 28 , were found Know guilty of conspiracy Committing_crime to murder. < ref name= '' Four guilty over 21/7 bomb plot '' > < /ref > The four attempted bombers were each sentenced Legal_rulings to life imprisonment Prison , with a minimum of 40 years ' imprisonment Prison .