The reason "why did 9" is ambiguous, but based on search results the likely intended question is "Why did 9/11 happen?" or "Why did the 9/11 attacks occur?" The 9/11 attacks were carried out by the terrorist group al-Qaeda, led by Osama bin Laden. Several factors contributed to the attacks, including Islamic extremism fueled by political events like the Iranian Revolution, the Soviet invasion of Afghanistan, and U.S. support for Israel and certain Arab regimes. The attackers sought to inflict widespread psychological and physical harm by hijacking airliners and crashing them into symbolic U.S. targets such as the World Trade Center and the Pentagon, resulting in nearly 3,000 deaths. The attacks were a culmination of longstanding grievances and extremist ideology, and they triggered the U.S.-led "War on Terror," including invasions of Afghanistan to dismantle al-Qaeda bases and the Taliban regime that harbored them.

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