Former President George W. Bush and Condoleezza Rice described a 'horrible moment' in the White House bunker after 9/11 when they believed United Airlines Flight 93 had been shot down, as they coordinated the domestic response and grounded civilian flights.
On September 11, 2001, the United States experienced the worst terrorist attack in its history when two planes crashed into the World Trade Center's Twin Towers in New York City, another plane hit the Pentagon in Arlington, Virginia, and a fourth plane crash-landed in Pennsylvania. The attacks, carried out by terrorists linked to al-Qaeda, resulted in the deaths of thousands of people and led to the largest emergency-service response in American history. President George W. Bush declared a war on terrorism, and the subsequent Operation Enduring Freedom aimed to oust the Taliban regime in Afghanistan and destroy Osama bin Laden's terrorist network. The Office of Homeland Security was established, and the 9/11 Memorial & Museum now stands as a place of remembrance and contemplation.