There are literally hundreds of conspiracy theories. That fact is 18 of 9-11 Islamist skyjackers came with student visas, except for Hanjour who came with a tourist visa.
Conspirators in the 1993 bombing of the World Trade Center by Islamic terrorists included Ramzi Yousef, Mohammad Salameh, Abdul Yasin, Mahmoud Abouhalima, Ahmed Ajaj, Nidal Ayyad, and Eyad Ismoil