How NATO responded to 9/11

NATO's Article 5 has been invoked once—after 9/11

The article was invoked the day after the attacks and launched a series of NATO campaigns to fight global terrorism. This page includes excerpts from a speech by then-NATO Secretary General Jens Stoltenberg about the attacks and the organization’s response.

Members decide to what extent they respond to an attack on an ally

The NATO constitution is intentionally vague about what exactly is required from its members. Explore the historical debates and learn more about common misconceptions about NATO’s common defense clause.

The treaty's Article 5 requires mutual defense, but not necessarily military action

Article 5 of the North Atlantic Treaty established NATO’s principle of collective defense. This resource examines the historical context, legal interpretations, and practical applications of this commitment, including its sole invocation after the Sept. 11 attacks.

How NATO works

NATO now includes 32 member nations—but how does the alliance actually function? This explainer breaks down its structure, decision-making process, and funding model. From its founding in 1949 to its collective response after 9/11, here’s how NATO operates on a global scale.

The alliance operates under a "flexible response" doctrine—that is, proportionality

NATO countries' main deterrent against aggression is their ability to respond with nuclear weapons. This video from "The Infographics Show" outlines the purpose of this nuclear arsenal, NATO’s strategy to prevent attacks, and its plans in the event of escalation toward nuclear war.

Watch the historic treaty signing that established NATO in 1949

NATO was created with the signing of the North Atlantic Treaty on April 4, 1949, in Washington, DC. The clip embedded in the webpage includes a newsreel with an excerpt from US President Harry Truman’s speech celebrating the historic day.

NATO was formed in 1949 to deter Soviet expansion and integrate Europe

Europe was in shambles after World War II, which saw 36 million Europeans killed, and the Soviets were looking to increase their influence. Beyond deterring the Soviets, the alliance sought to restore Europe and prevent nationalist militarism akin to the German Nazis and Italian Fascists.

NATO condemned Russia's 2022 invasion of Ukraine

While Ukraine is not a member, NATO responded forcefully to the Russian invasion of the country in 2022. This page from the NATO website offers answers to frequently asked questions about NATO’s response to the invasion, specifically on how NATO is aiding Ukraine.

The 2001 Authorization for Use of Military Force has been used by four administrations to justify military operations in 22 countries

Passed three days after the September 11 attacks to authorize the use of force against al-Qaeda and the Taliban, the 2001 AUMF has since been stretched far beyond its original scope and has been used by four consecutive administrations to justify military operations.

Smithsonian artifacts that tell the story of 9/11 (w/photos)

Hundreds of objects linked to the attacks, from office supplies recovered at the World Trade Center to firefighters’ gear used at the Pentagon to fragments pulled from the crash site of Flight 93, reside in the national collection. Read about 31 Smithsonian artifacts that help unravel the complex story of 9/11 and its aftermath.

The attacks prompted a quick jump in American public support for war

In a Gallup poll taken days after the attack, an extraordinary 97% of Americans approved Congress declaring war on Japan—reflecting overwhelming national unity in the wake of the strike.

Coverage of the 9/11 terrorist attacks helped shape Wikipedia's editorial policies

Launched nine months earlier, the site was featured on Yahoo's news page, attracting traffic from information seekers as dozens of new editors created hundreds of articles, including memorials, conspiracy theories, and donation and volunteer pages. Discussions between editors would begin establishing rules for handling breaking news events.

The National Security Council advises the president on foreign policy and national defense

Created in 1947, the NSC coordinates military, diplomatic, and intelligence policy matters. Chaired by the president, it includes key Cabinet officials and senior advisers who shape American responses to global crises and security threats.

Should the US have entered into World War I?

America entered World War I in 1917, but had remained neutral until that point. President Woodrow Wilson addressed Congress, further underlining the USA's neutrality. Eleven weeks later, he asked for a declaration of war. With attacks by German saboteurs on an American munitions depot, it seemed he had no choice. But did he? This article asks what might have happened if the US stayed out of WWI.

Watch Springsteen open a somber 9/11 tribute

“America: A Tribute to Heroes” was a fundraising telethon on Sept. 21, 2001, and simulcast across the four major networks. Springsteen opened the program with “My City of Ruins,” a song originally written about Asbury Park that took on new significance after the Sept. 11 terrorist attacks.

A 1983 NATO war simulation provoked the Soviets to prepare for war

The "SNAFU" podcast, hosted by actor and comedian Ed Helms, explores some of the biggest blunders in history. Season one focuses on the 1983 NATO Able Archer military exercise, a war game that simulated nuclear attacks on the Soviet Union. The USSR mistook the exercise for a genuine threat and prepared its forces for war. Helms recounts this almost catastrophic event in world history with his signature humor.

FDR stayed composed as he absorbed the news of Pearl Harbor

This video reconstructs Roosevelt’s steady, methodical response on Dec. 7, 1941, from his first briefing to drafting his speech to Congress. It demonstrates how FDR maintained composure and moved rapidly to prepare the nation for war.

Why the First Gulf War occurred—and how it played out

This video navigates the conflict’s core—from Iraq's August 2, 1990 invasion of Kuwait through Operation Desert Shield’s buildup, to the decisive air and ground assault of January–February 1991. It spotlights coalition tactics and rapid liberation of Kuwait, highlighting how precision bombing and advanced tech reshaped modern warfare.

At 3 pm on Memorial Day, Americans are asked to pause for one minute of silence

President Bill Clinton first called for the National Moment of Remembrance in 1999, and Congress made it law in 2000. The time was chosen because most Americans are in the middle of holiday activities.

The US Constitution has influenced rights and governments worldwide

This interactive tool from the National Constitution Center allows you to compare constitutional rights globally, highlighting which countries have adopted protections similar to those in the US Constitution—and how shared principles manifest in different legal forms around the world.

The Federal Emergency Management Agency leads the US response to disasters

Established in 1979, FEMA coordinates the government's response to hurricanes, wildfires, floods, and other disasters, providing funding, logistical support, and recovery assistance. In FY 2024, the agency spent $35.1B, nearly 40% of the Department of Homeland Security's total budget.

Watch an American news report of the Chernobyl disaster

Americans first heard about the Chernobyl nuclear disaster two days after the event, once abnormal radiation was detected in nearby countries. This forced Soviet officials to acknowledge the catastrophe publicly for the first time a few days after it occurred.

Exploring Kristallnacht

Nov. 9 and 10, 1938, saw Nazi members break into Jewish stores and homes across Germany in retaliation for the assassination of a German diplomat by a Polish Jew. The event—called "Kristallnacht," meaning "night of the broken glass"—was tacitly condoned by the German authorities at the time. This richly produced interactive explores the events of Kristallnacht guided by one of its survivors, Charlotte Knobloch.

The G20 emerged from the 1997 Asian financial crisis as a forum for managing the global economy

Established in 1999 and elevated to a leaders' summit during the 2008 financial crisis, the G20 now unites the world's largest economies to address issues that the Bretton Woods institutions were not designed to manage.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

What happens if the US doesn't pay its debt?

A video created during the debt ceiling debates of 2021 outlining what would happen if the US failed to meet its debt obligations. Its lessons are applicable to today's debates.

The US first hosted the World Cup in 1994, a tournament that lives in soccer infamy for its poor planning and the murder of Colombian player Andres Escobar, who'd accidentally scored on his own net.

View the ten deadliest tornadoes in US history.

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in casualties, forces mobilized, and displacement of civilians.

A 2019 Facebook event called on attendees to "Storm Area 51, They Can't Stop All of Us," resulting in countless memes, the creation of a music festival, and eventually the arrests of those who did try to approach the area.

Explore an interactive map of battles from the American Revolution, along with detailed summaries of each engagement

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

Experimental hantavirus vaccines and therapies, still under development, have long been funded by the US military.

The idea for the Federal Reserve was conceived in secret in 1910—with bankers donning duck hunt gear for disguise while traveling to a remote country club on Georgia's Jekyll Island

Watch contemporary footage covering the US-backed Shah of Iran fleeing the country in the face of the 1979 Iranian Revolution

US consumers collectively owe more than $1T to credit card companies—almost as much as they owe in auto loans.

The identity of the Tank Man in the iconic photo from the 1989 Tiananmen Square protests remains unknown and was possibly killed.

After NASA's Voyager 1 captured Earth as a single pixel as it left the solar system in 1990, astronomer Carl Sagan used the image to reflect on humanity's fragility and the responsibility to protect 'the only world we've ever known.'

American dance legend Martha Graham, sometimes called 'the Picasso of dance,' refused to perform at the 1936 Olympics in Berlin and conceived the piece 'Chronicle' in response to the experience.

The Nasdaq's 'Magnificent 7' companies are responsible for roughly 40% of the Nasdaq 100 index's gains, while the remaining 93 companies account for the other 60%.

The most expensive ad of all time was for Chanel No. 5 perfume and cost roughly $33M to produce in 2004—about $57M in today's dollars.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

In recent years a child anxiety expert has created and tested a novel phobia and anxiety treatment approach for children, focused on changing how parents respond to the fears.

Poison ivy's characteristic rash is caused by an allergic response to an oily compound in the plant called urushiol.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

Explore a list of the 100 best novels of all time, compiled by some of the world's best living writers, including Salman Rushdie, Stephen King, and Jennifer Egan.

Waves off the coast of Nazaré, Portugal, can reach over 100 feet and are caused by the area's deep underwater canyon geography

Tattoos remain visible on your skin thanks to immune cells called macrophages