https://ctc.westpoint.edu/the-mysterious-relationship-between-al-qaida-and-iran/

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The evidence for a secret relationship between al-Qa`ida and Iran is significant, but largely limited and the facts quite murky. The 9/11 Commission’s report concluded that there is evidence of contacts among al-Qa`ida, the Iranian government and Iran’s Lebanese Hizb Allah ally dating back to Usama bin Ladin’s years in Khartoum in the mid-1990s.1 During this time, it is possible that Hizb Allah provided some training to future al-Qa`ida operatives, as Sudan was a watering hole for virtually every terrorist and extremist group in the Middle East. As a result, it would not be surprising for the nascent al-Qa`ida group to have encountered the Iranian Revolutionary Guard Corps (IRGC) and the Iranian Ministry of Intelligence (MOIS).

Some sources, including the 9/11 Commission, have suggested more than mere contact, alleging that the two may have collaborated in the attack on the U.S. Air Force barracks in Khobar, Saudi Arabia in 1996. In the CTC Sentinel, however, Thomas Hegghammer made clear that the evidence for such collaboration is unconvincing.2 Moreover, evidence that emerged in the decade after the attack, reviewed by the author, also suggests that al-Qa`ida did not have involvement in the Khobar attacks.3 Bin Ladin has said the same.4

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