On September 11, 2001, the Islamic terrorist group al-Qaeda orchestrated a series of coordinated suicide attacks on the United States, with 19 hijackers seizing four commercial airliners. Two planes, piloted by Mohamed Atta and Marwan al-Shehhi, crashed into the Twin Towers of the World Trade Center in New York City, a third struck the Pentagon in Virginia, and a fourth crashed into a rural Pennsylvania field after passengers revolted, thwarting an attack on the U.S. Capitol or White House. The attacks killed 2,977 people, caused at least $10 billion in damage, and remain the deadliest terrorist incident in history, also marking the deadliest single event for U.S. firefighters (343) and law enforcement (72). In response, President George W. Bush launched the Global War on Terror, invading Afghanistan and invoking NATO's Article 5 for the first time, while al-Qaeda leader Osama bin Laden was eventually killed by U.S. forces in Pakistan in May 2011. The aftermath brought long-term health crises for responders, global market shocks, and stricter anti-terrorism laws worldwide, with the Costs of War Project estimating that the attacks and subsequent conflicts have led to over 4.5 million total deaths. The cleanup of the World Trade Center site, known as "Ground Zero," was completed in May 2002, marking a physical end to the immediate recovery but leaving a profound and lasting impact on global politics and security.