The events of September 11, 2001, set in motion sweeping changes to U.S. intelligence and counterterrorism practices, launched two major wars, and altered Americans’ daily routines. This timeline traces three pivotal years whose reverberations continue today.
In the deadliest terrorist assault in U.S. history, nineteen al-Qaeda members hijack four commercial airliners and crash two into the World Trade Center towers in New York City and one into the Pentagon outside of Washington, DC. The fourth plane crashes in rural Pennsylvania after passengers try to wrestle back control. The attacks, which killed 2,977 people, are the culmination of nearly a decade of efforts by Osama bin Laden—motivated by radical Islamist ideology—to kill American soldiers and civilians. Later investigations find that the hijackers, most of them Saudi nationals, entered the United States and attended flight training schools largely without raising alarms. CIA Director George Tenet later says that “the system was blinking red,” but despite White House briefings on the bin Laden threat, intelligence agencies and domestic law enforcement failed to share crucial information.
President George W. Bush visits Manhattan to address rescue workers at the World Trade Center site, a ten-block area of rubble that ultimately takes nine months to clear. Later that day, speaking at the Washington National Cathedral, Bush vows to “answer these attacks, and rid the world of evil.” He also declares a national state of emergency, which gives him expanded powers to mobilize the military. A week later, he issues a second emergency declaration that grants the executive branch sweeping powers to target terrorist financing around the world. These emergency declarations are renewed each year by Bush and subsequent presidents and remain in force today.
In a secret memorandum, Bush grants the CIA new and open-ended authority to capture and detain anyone who it determines poses a “continuing, serious threat” [PDF] to the United States. Previously, the CIA had only a limited ability to detain specific individuals pending legal charges. The directive sets in motion what eventually becomes a sprawling global network of CIA “black sites,” or unofficial, undisclosed detention and interrogation centers. The first such detainee, commonly known as Abu Zubaidah, is captured in Pakistan in March 2002 and transferred to a black site in Thailand.
A spate of letters containing anthrax, a highly lethal virus, are delivered to newsrooms and congressional offices just a week after the 9/11 attacks, killing five people and sparking nationwide alarm. The letters’ allusions to Islamist ideology and the refined nature of the anthrax raise fears that the biological attacks are state-sponsored; The White House and U.S. intelligence agencies point the finger at Iraqi dictator Saddam Hussein. However, many initial findings are later discredited, and the FBI, following its largest investigation to date, eventually pins the blame on American scientist Bruce Ivins. After Ivins commits suicide in 2008, the FBI closes the case, though many questions remain, including about Ivins’s culpability.
Bush signs a joint resolution of Congress authorizing the president to use “all necessary and appropriate force” against those who “planned, authorized, committed, or aided” the 9/11 attacks, or who harbored anyone who did. The Bush administration initially uses the Authorization for Use of Military Force (AUMF) to go after al-Qaeda and its Taliban sponsors in Afghanistan but later expands its scope to include any forces “associated” with al-Qaeda around the world. The AUMF becomes the basis [PDF] for U.S. military actions in at least fourteen countries across Africa, the Middle East, and South Asia, including the proliferation of drone strikes under President Barack Obama, which raises ongoing concerns that the authorization is used far beyond its original intent.
In an address before a joint session of Congress, Bush outlines what he describes as a global, open-ended “war on terror” and announces the creation of an Office of Homeland Security to protect the United States from future attacks. He demands that the Taliban government in Afghanistan hand over all al-Qaeda members on its soil, including bin Laden, and warns the world that “either you are with us or you are with the terrorists.” The U.S. government uses the term “global war on terror” to describe its far-reaching military response to the 9/11 attacks and its new, sweeping domestic counterterrorism measures until the designation is officially retired by Obama.
After the North Atlantic Treaty Organization (NATO) invokes its collective self-defense mechanism for the first time, U.S. and UK forces begin air strikes against targets in Afghanistan. Ground forces follow within days. The U.S.-led invasion, called Operation Enduring Freedom, is supported by local anti-Taliban forces and troops from twenty-seven coalition countries. By December, the Taliban government collapses, but bin Laden evades capture. NATO assumes command of international security operations in 2003, and the occupation and counterinsurgency mission in Afghanistan continues for nearly two decades.
Bush signs the Patriot Act, legislation that aims to strengthen the federal government’s counterterrorism response. The expansive bill includes provisions to bolster cooperation between law enforcement and intelligence agencies; strengthen banking regulations to combat terrorist financing; create new definitions and penalties for terrorist activity; and dramatically expand domestic surveillance. Critics allege that the law is too broad and was rushed through. Press reports later reveal a massive collection of Americans’ phone records by the National Security Agency (NSA) based on Patriot Act authorities [PDF], which prompts Congress to place new limits on domestic surveillance.
Bush signs legislation to create the federal Transportation Security Administration (TSA), which assumes responsibility for airport security from private firms. In the coming years, the TSA rolls out a host of new passenger-safety procedures and restrictions following a series of failed airline plots, beginning with Richard Reid’s attempted shoe bombing in December 2001. The measures include luggage screenings, full-body scanners, shoe removal, pat-downs, restrictions on liquids, increased scrutiny of personal electronics, and limitations on in-flight movement. Critics say the new status quo is an expensive and likely ineffective overreaction that leads to unnecessary delays as well as ethnic and religious profiling.
The first terrorism detainees arrive at the U.S. Naval Station Guantanamo Bay, a military outpost that has been leased from Cuba since 1903. The new detention facility is initially used to hold suspected al-Qaeda and Taliban fighters captured in Afghanistan, but individuals held by the CIA at black sites, including alleged 9/11 planner Khalid Sheikh Mohammed, are later transferred there. The facility becomes a lightning rod for international criticism of the Bush administration’s counterterrorism policies, fueled by accusations of torture and other mistreatment of detainees violating international norms. At its peak, Guantanamo held more than five hundred detainees; thirty-nine remain today.
In his first State of the Union address since 9/11, Bush welcomes the transitional leader of Afghanistan, Hamid Karzai, and warns that “our war against terror is only beginning.” Noting U.S. military deployments in the Philippines, Somalia, and elsewhere, he says that Washington will oppose “outlaw regimes” anywhere in the world. He singles out Iran, North Korea, and Iraq—citing Baghdad’s purported development of anthrax—as an “axis of evil.” Critics, including some EU and UK officials, say the speech undermines diplomatic efforts. Some analysts contend that it sours Iran’s budding cooperation with the United States in Afghanistan and contributes to North Korea’s withdrawal from the Nuclear Nonproliferation Treaty in 2003.
Top Bush administration lawyers issue the first [PDF] in a series of classified memos providing legal justification for a wartime president to authorize “enhanced interrogation” methods such as waterboarding, stress positions, and extended sleep deprivation. The controversial guidance, which is not revealed publicly until 2004, asserts that such practices do not constitute torture. The administration also claims that al-Qaeda and Taliban fighters are not entitled to Geneva Convention protections for prisoners of war. In 2009, the incoming Obama administration, which considers the techniques torture, bans them. In 2014, the Senate Select Committee on Intelligence releases its highly critical investigation into the CIA’s interrogation program, finding the techniques to be counterproductive for intelligence gathering.
In a speech before the UN General Assembly, Bush delivers an ultimatum to Saddam’s government, which he calls a “grave and gathering danger.” He accuses Iraq of violating a slew of UN Security Council resolutions dating back to 1991, including its obligations to destroy all weapons of mass destruction (WMD) and allow weapons inspectors unfettered access to facilities. He also says Iraq has refused to end its support for terrorist organizations, including al-Qaeda, whose members Bush says “are known to be in Iraq” despite U.S. intelligence doubts. He warns that Baghdad is developing chemical, biological, and nuclear weapons that could be passed to terrorist groups, an assertion that is contested by many U.S. allies, and says that the United States will act alone if necessary.
Bush signs into law a second authorization for use of military force (AUMF), which allows him to defend against “the continuing threat posed by Iraq” and cites the Saddam government’s purported harboring of al-Qaeda and other terrorist groups and its alleged stockpiles of WMD. Critics later claim that subsequent presidents abused the 2002 AUMF to conduct unrelated military operations, including the Obama administration’s 2014 offensive against the self-proclaimed Islamic State in Iraq, and the Donald Trump administration’s 2020 killing of Iranian commander Qasem Soleimani in Baghdad.
After weeks of U.S. diplomacy to convince skeptics including China, France, and Russia, the UN Security Council unanimously adopts a resolution giving Baghdad “a final opportunity to comply with its disarmament obligations” and ordering the deployment of international weapons inspectors. Saddam agrees, and on November 27 inspectors from the United Nations and the International Atomic Energy Agency return to Iraq. In the coming months, inspectors find a cache of aged chemical warheads and several banned missiles but conclude that they are remnants of previous weapons efforts. They find no evidence of an ongoing WMD program. The Bush administration, which asserts that Saddam is hiding evidence, begins a push for a second UN resolution to explicitly authorize international military force against Iraq.
Bush signs legislation creating the cabinet-level Department of Homeland Security (DHS). The broadest reorganization of the federal government since World War II, the law centralizes more than twenty disparate domestic security functions under the aegis of DHS. These include immigration and border agencies; the TSA; the Coast Guard; the Secret Service; the Federal Emergency Management Agency (FEMA); and various nuclear and cybersecurity agencies. Supporters say the new arrangement boosts coordination between agencies and prevents the kind of intelligence gaps that led to the 9/11 attacks. Critics say it does little to improve cooperation between the FBI and CIA, duplicates essential functions, contributes to the militarization of local police forces, and threatens civil liberties.
Secretary of State Colin Powell lays out the administration’s most comprehensive case for an invasion of Iraq, centered on claims of an active WMD program and Iraqi ties to al-Qaeda. The presentation at the United Nations comes days after Bush asserts that Saddam is seeking nuclear material from Africa, a claim unsupported by U.S. intelligence. Despite Powell’s assertions, multiple post-invasion investigations, including by the U.S.-led Iraq Survey Group and the bipartisan Iraq Intelligence Commission [PDF], find no evidence of collusion between Iraq and al-Qaeda nor of an active Iraqi weapons program.
After Washington’s attempt to win UN support fails, a coalition primarily consisting of U.S. and UK forces invades and quickly overwhelms the Iraqi Army. On May 1, Bush declares the end of major combat operations, but it is only the beginning of nearly a decade of occupation and counterinsurgency. U.S. troop levels peak at [PDF] more than 160,000 in 2008. The conflict—including the invasion, the resulting civil war, and the subsequent rise of the Islamic State—kills nearly five thousand U.S. service members and an estimated half million Iraqis and costs the U.S. government some $2 trillion. UN Secretary-General Kofi Annan maintains that the invasion violates international law, and weapons inspectors end their search in 2005 having never found WMD.
A bipartisan national commission created by Congress to investigate 9/11 releases its findings, concluding that the success of the plot was due to multiple intelligence failures, particularly a lack of communication between intelligence agencies and domestic law enforcement. The report also points to weaknesses in immigration and aviation security systems as well as a general inability across government to grasp the threat of transnational terrorism. It leads to the creation of the National Counterterrorism Center within the Office of the Director of National Intelligence to coordinate the efforts [PDF] of the CIA, NSA, and other intelligence services. The report finds no Iraqi connection to the attacks, and its conclusion that the government of Saudi Arabia was not involved spurs ongoing controversy.