Osama bin Laden Al-Qaeda leader Osama bin Laden, 1998. (more) Who Planned the September 11 Attacks? Ask the Chatbot a Question More Actions Share Share Share to social media Facebook X URL https://www.britannica.com/topic/Who-planned-the-September-11-attacks Feedback Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login). Feedback Type Select a type (Required) Factual Correction Spelling/Grammar Correction Link Correction Additional Information Other Your Feedback Submit Feedback Thank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article.

　　External Websites Ask the Chatbot a Question Written by The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... The Editors of Encyclopaedia Britannica Last Updated: Sep 16, 2025 • Article History Table of Contents Table of Contents Ask the Chatbot Al-Qaeda leader Osama bin Laden is considered the mastermind of the September 11 attacks, though Khalid Sheikh Mohammed was the operational planner. Mohammed came up with the tactical innovation of using hijacked planes to attack the United States, and al-Qaeda provided the personnel, money, and logistical support to execute the operation. Mohammed Atta was selected to head the operation. He and 18 other terrorists, most of whom were from Saudi Arabia, established themselves in the United States, where some received commercial flight training. All 19 hijackers died in the attacks, bin Laden was killed by U.S. forces in 2011, and ...(100 of 105 words)

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