What happened on September 11?
On September 11, 2001, 19 al-Qaeda terrorists hijacked four commercial airplanes in the United States. Two were crashed into the Twin Towers of the World Trade Center in New York City, one struck the Pentagon, and one crashed in Pennsylvania after passengers fought back. Nearly 3,000 people were killed in the deadliest terrorist attack in history, triggering the global War on Terror.
The attacks of September 11, 2001, were a singular event that reshaped American foreign policy, global security, and the daily lives of billions of people. In a few hours on a clear Tuesday morning, the post-Cold War world's sense of security was shattered.
Nineteen hijackers affiliated with the al-Qaeda terrorist network, led by the Egyptian Mohammed Atta, boarded four domestic flights with box cutters and knives. At 8:46 AM, American Airlines Flight 11 crashed into the North Tower of the World Trade Center. At 9:03 AM, United Airlines Flight 175 struck the South Tower — this time on live television, watched by millions. At 9:37 AM, American Airlines Flight 77 hit the Pentagon. United Airlines Flight 93, likely headed for the Capitol or White House, crashed in a field near Shanksville, Pennsylvania, after passengers — alerted by phone calls to the earlier attacks — attempted to retake the cockpit. The South Tower collapsed at 9:59 AM; the North Tower at 10:28 AM.
The death toll was 2,977 people from over 90 countries — office workers, firefighters, police officers, paramedics, airline passengers and crew. The attacks were planned and directed by Osama bin Laden, the Saudi-born leader of al-Qaeda, operating from Taliban-controlled Afghanistan. Bin Laden's stated motivations included American military presence in Saudi Arabia, U.S. support for Israel, and sanctions against Iraq — grievances embedded in a radical Islamist ideology that framed the West as waging war against Islam.
The consequences reshaped the world. The United States invaded Afghanistan in October 2001, toppling the Taliban regime and beginning what would become America's longest war (2001–2021). The 'War on Terror' expanded to Iraq in 2003 — a controversial decision justified by claims about weapons of mass destruction that proved false. Domestically, the Patriot Act expanded surveillance powers, the Department of Homeland Security was created, and airport security was transformed. Guantanamo Bay detention camp, extraordinary rendition, and enhanced interrogation techniques raised fundamental questions about civil liberties and human rights.
The attacks also had profound cultural and social effects. Islamophobia surged in Western countries. The security state expanded globally. The costs of the post-9/11 wars — trillions of dollars, hundreds of thousands of lives, the destabilization of the Middle East — continue to shape global politics. September 11 demonstrated that non-state actors could strike at the heart of the world's most powerful nation, and the response to that attack defined the first two decades of the 21st century.