This September, the United States will mark a somber milestone: the 25th anniversary of the deadliest terrorist attack ever carried out on American soil, the September 11, 2001 attacks. A full schedule of commemorative events is set to open across the country this Friday, honoring the thousands of lives lost forever on that clear Tuesday morning.
The coordinated attacks, carried out by 19 hijackers affiliated with the Islamist extremist network al-Qaeda, unfolded in less than two hours that day, leaving shock and devastation across the U.S. Northeast. Four commercial passenger jets traveling over the eastern United States were seized simultaneously by small groups of hijackers, who repurposed the large aircraft into lethal, guided weapons targeting iconic American landmarks.
Two of the hijacked planes were deliberately flown into the 110-story Twin Towers of the World Trade Center in Lower Manhattan, with the second impact hitting 17 minutes after the first. Intense infernos ignited across the upper floors of the skyscrapers, trapping hundreds of people above the crash sites and shrouding New York City in thick, toxic smoke. By mid-morning, both towers had collapsed into massive plumes of dust and debris, leaving a gaping hole in the city’s skyline and collective consciousness.
A third plane crashed into the western facade of the Pentagon, the U.S. military’s sprawling headquarters located just outside Washington, D.C. The fourth jet, whose hijackers reportedly intended to target the U.S. Capitol Building in Washington, crashed into a rural field in Somerset County, Pennsylvania, after passengers and crew fought back against the attackers, preventing further loss of life in the nation’s capital.
When the dust settled, the final death toll stood at 2,977 people, not including the 19 hijackers who carried out the plot. All 246 passengers and crew across the four planes were killed, 125 people died at the Pentagon, and 2,606 perished at the World Trade Center – either in the collapse itself or from long-term injuries and illnesses related to the attack. Victims ranged in age from two-year-old Christine Lee Hanson, the youngest, to 82-year-old Robert Norton, the oldest, both of whom were passengers on the hijacked flights. Citizens of 77 different nations were counted among the dead, and 441 first responders from New York City made the ultimate sacrifice responding to the attack.
While an estimated 17,400 people were inside the two towers when the first plane struck, no one above the impact zone in the North Tower survived. In the South Tower, 18 people managed to escape from floors above the impact zone before the building collapsed. The long-term health toll of the attack has been staggering: thousands of survivors, first responders, and nearby residents have developed chronic illnesses linked to exposure to toxic dust and smoke from the towers’ collapse, and to date, these secondary health complications have claimed more than three times the number of lives lost in the original attack.
The plot to carry out the 9/11 attacks was masterminded by al-Qaeda, the extremist network led by Osama bin Laden, which operated from a base in Afghanistan. The group’s ideological leader, Khalid Sheikh Mohammed, an engineer who had studied in the United States and fought in Afghanistan during the 1980s, was the architect of the attack, and he helped recruit and train the hijackers, several of whom completed flight training inside the U.S. Fifteen of the 19 hijackers were Saudi citizens, like bin Laden, with two from the United Arab Emirates, one from Egypt, and one from Lebanon.
Within weeks of the attacks, then-U.S. President George W. Bush launched an international coalition invasion of Afghanistan with two core goals: dismantle al-Qaeda and capture or kill bin Laden. The manhunt for the al-Qaeda leader stretched on for a decade: it was not until 2011 that U.S. special operations forces located and killed bin Laden during a raid in Abbottabad, Pakistan. Khalid Sheikh Mohammed had been captured years earlier, during a 2003 raid in Pakistan.
After his arrest, Mohammed was held for three years in secret CIA detention facilities, where U.S. Senate Intelligence Committee investigations confirmed he was subjected to brutal interrogation tactics. He was later transferred to the U.S. military detention facility at Guantanamo Bay, Cuba, where he has remained in custody ever since. Legal proceedings to try Mohammed and three co-defendants for their role in the 9/11 attacks have dragged on for more than a decade, delayed by disputes over the admissibility of evidence obtained through coercive interrogation. A 2025 plea deal that would have seen Mohammed and two other co-accused plead guilty in exchange for avoiding the death penalty – receiving life without parole instead – was scrapped in July 2025 after federal officials objected to the agreement. The trial is now scheduled to begin in June 2028.
Nearly 20 years after the U.S.-led invasion, American troops completed their full withdrawal from Afghanistan in 2022, a move that sparked widespread concern that al-Qaeda – which still operates today, with its strongest presence in Sub-Saharan Africa and residual membership inside Afghanistan – could rebuild its operational capacity and launch new large-scale attacks.
The 9/11 attacks triggered lasting changes to global security and infrastructure in the decades that followed. Governments around the world enacted sweeping reforms to tighten commercial aviation security. In the U.S., the attacks led to the creation of the Department of Homeland Security, tasked with preventing future terrorist attacks, and the Transportation Security Administration, which oversees security protocols at all American airports.
Cleanup operations at the World Trade Center site, known widely as Ground Zero, took more than eight months to complete. Today, the site has been reborn: a permanent memorial and museum honoring the victims sits at the foot of the new World Trade Center complex, anchored by One World Trade Center – also called the Freedom Tower. Standing at 1,776 feet, the skyscraper rises 400 feet higher than the original North Tower it replaces, a symbol of resilience and renewal. Reconstruction of the damaged section of the Pentagon was completed in less than a year, with military staff back in their offices by August 2002.