On September 11, 2001, hijackers flew commercial airliners into the two World Trade Center towers and the Pentagon; a fourth plane heading for another Washington, D.C., target was taken over by the passengers after it was hijacked, and crashed in Pennsylvania. Intense fires from the jet fuel caused the twin towers to collapse not long after impact. Almost 3,000 people died in the worst attack on American soil since Pearl Harbor. Osama bin Laden and al Qaeda were identified as the principal suspects. Within a matter of days Congress gave the president authority to use military force against the perpetrators and their supporters; the mutual defense provision of the NATO treaty was implemented for the first time to support any American action. Operation Enduring Freedom against the Taliban government in Afghanistan, which provided material help to al Qaeda and tolerated its training camps, began in October. American and British forces along with anti-Taliban Afghanis in the Northern Alliance overthrew the government by the end of the year; Hamid Karzai was chosen as the interim prime minister. Osama bin Laden and the al Qaeda leadership, however, escaped capture.
In late 2002, the National Commission on the Terrorist Attacks Upon the United States, better known as the 9/11 Commission, was established. The independent, bipartisan commission was charged with investigating the attacks, the response to them, and making recommendations on the prevention of future attacks. The Commission's 2004 report, which became a national bestseller, noted that terrorism was not a high priority for the government over several administrations, and pointed to specific problems in dealing with the threat by the FBI, CIA, and aviation security. The Commission also expressed concern over the difficulties in sharing intelligence information among various agencies. The Bush administration did implement several of the Commission's recommendations — the appointment of a National Intelligence Director and the creation of a National Counterterrorism Center among them.
There were domestic consequences to the attacks of September 11. The USA Patriot Act (2001) made it easier for law enforcement and intelligence agencies to share information, expanded the authority of the federal government to conduct searches and surveillance, and provided for the detention/deportation of aliens suspected of terrorism. The act was often criticized for undermining civil liberties; greater protection for individual rights were included in the legislation's 2006 reauthorization. Although initially opposed by the president, the Department of Homeland Security was established in 2003. The new executive department consolidated the work of 22 federal agencies responsible for preventing and responding to a terrorist attack or other threat to the United States. The Federal Emergency Management Agency (FEMA), the U.S. Citizenship and Immigration Service (formerly the Immigration and Naturalization Service), the U.S. Coast Guard, the U.S. Customs and Border Protection (formerly U.S. Customs Service and U.S. Border Patrol), and the U.S. Secret Service now all fall under Homeland Security.