NATO was founded in 1949.

NATO was formed in 1949 to deter Soviet expansion, prevent European militarism, and encourage political integration.

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

How NATO responded to 9/11

The collective defense clause of the NATO constitution has only been invoked one time: after the 9/11 terrorist attacks against the United States. This video explores the immediate actions NATO took to respond to the attacks to support the United States. These firsthand clips from 2001 give a sense of the magnitude of the moment and the difficult decisions facing NATO leaders at the time.

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.

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 consists of 32 countries across North America and Europe.

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 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.

As of 2025, every NATO member spent at least 2% of GDP on defense, a target the alliance had been pushing toward for over a decade.

Decisions at NATO are by consensus and must be unanimous

There are two strategic commands in NATO: one in Europe (Supreme Allied Headquarters Command Europe) and another in Norfolk, Virginia (Allied Command Transformation). The alliance is headed by both a military officer and a civilian leader.

The 1941 Atlantic Charter was a World War II alliance and model for the UN

The Atlantic Charter was a pivotal 1941 agreement between Franklin D. Roosevelt and Winston Churchill, outlining shared goals for a post-World War II world rooted in freedom and self-determination. These ideals later inspired the founding principles of the United Nations.

The 1955 Warsaw Pact was the Soviet Union’s answer to NATO

The pact included Albania, Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, Romania, and the USSR. The pact established collective security and a joint military command between the member countries.

The Cold War (1947-1991) prompted the birth of NATO and the Soviet Warsaw Pact

The geopolitical rivalry between the United States and Soviet Union was considered “cold" because the two countries never directly engaged in military combat during the time period. This page from the Kennedy Presidential Library outlines the causes and major events of the early Cold War.

Tensions between the US and European NATO allies

The Associated Press article discusses US Defense Secretary Pete Hegseth's assertion in February of 2025 that restoring Ukraine's prewar borders or NATO membership for the country are both unrealistic. This represented a large rift between the United States and its other NATO allies, prompting concern about America’s commitment to the future of the alliance.

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.

Finland and Sweden joined NATO after Russia's invasion of Ukraine

In response to Russia's 2022 invasion of Ukraine, Finland and Sweden abandoned decades of military neutrality to join NATO, marking a major shift in Europe's security landscape and expanding the alliance to Russia's borders.

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

Germany is pursuing its most significant military buildup since WWII.

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.

General Jennie Carignan was the first woman to lead a NATO mission

"NATO Through Time" is a podcast exploring NATO's history and its impact on today's world. This episode features General Jennie Carignan, Canada's top military leader, as she shares insights from her NATO missions in Bosnia, Afghanistan, and Iraq.

NATO leads cyber war games in Estonia

Estonia is host to one of the world’s largest annual interactive cybersecurity drills. Russia is always considered the main threat, but this year, the war in Ukraine has only added to the stakes.

Wartime conferences exposed cracks in the US–Soviet alliance

At the Tehran, Yalta and Potsdam Conferences, Allied leaders coordinated WWII strategy—but deep disagreements over postwar Europe foreshadowed the Cold War. The USSR’s push for influence in Eastern Europe clashed with US and British calls for self-determination.

The League of Nations was the predecessor to the UN—and the US never joined

The League of Nations—established in 1920 after World War I—was the first global organization aimed at maintaining world peace. Although US President Woodrow Wilson championed its creation, the United States never joined.

How Stalin, Roosevelt, and Churchill shaped the postwar world

The Yalta Conference was a pivotal 1945 meeting between Allied leaders that helped shape the postwar global order and laid the groundwork for the founding of the United Nations.

The Truman Doctrine marked the start of US containment strategy

Introduced in 1947, the Truman Doctrine pledged US support for nations resisting communism—starting with Greece and Turkey—and launched the containment policy that defined early Cold War strategy.

The United Nations was founded in San Francisco in 1945.

The Nazis and Soviets agreed to a non‑aggression pact in 1939

On August 23, 1939, Nazi Germany and the Soviet Union signed the Molotov–Ribbentrop Pact—a public commitment to not attack each other combined with a secret agreement dividing Eastern Europe into spheres of influence. This pact enabled Germany to invade Poland unopposed from the east and delayed conflict with the USSR until June 1941.

The threat of nuclear annihilation reshaped global diplomacy

The first use of atomic weapons introduced the possibility of a war with no survivors. This article examines how nuclear fear shaped Cold War diplomacy and continues to influence international relations today.

Since World War II, formal declarations of war and peace treaties have become increasingly rare, replaced by cease-fires, authorizations of force, and "special military operations."

9/11 reshaped US foreign and military policy for decades, shifting focus to non-state actors and the Middle East.

The US launched the Global War on Terror after 9/11

In the wake of 9/11, the US declared a Global War on Terror—initiating military operations in Afghanistan and Iraq, expanding surveillance, and forming international coalitions to combat terrorism and disrupt extremist networks worldwide.

NASA was created in 1958 in the wake of the Sputnik 1 launch

The launch of Sputnik 1 in 1957 jolted US political leaders, who urgently consulted scientists and defense experts on how to respond. Concerns about Soviet technological dominance—and the promise of civilian space applications—led directly to NASA’s creation in 1958.

How the NSA has changed through history

The National Security Agency was born in the Cold War and then transformed by 9/11. This article answers all the basic questions you might have about the NSA, from what it does to how much data it collects to some of its useful intercepts.

The Bretton Woods conference in 1944 created the foundations of the modern global economy

In July 1944, 44 nations gathered in Bretton Woods, New Hampshire, to create a new postwar economic order. The conference led to the creation of the IMF and the International Bank for Reconstruction and Development—now known as the World Bank.

al-Qaida was founded in 1988 by Osama bin Laden

The group emerged in 1988 from the militant networks formed during the Soviet-Afghan War. Under Osama bin Laden's leadership, it combined jihadist ideology with global ambitions—eventually orchestrating attacks across Africa, the Middle East, Europe, and the United States.

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.

Questions about the US' commitment to its allies may have sparked a new nuclear age

Some US allies—from Warsaw to Seoul—are reevaluating their security amid doubts over American nuclear commitment, signaling the possibility they may want to acquire their own weapons.

The formation of the UN elevated the US on the world stage

This podcast episode of "To the Best of My Ability" from the National WWII Museum goes behind the scenes of the United Nations' founding from the American perspective. It explores how FDR's vision for global peace took shape, how Truman carried it forward, and how Eleanor Roosevelt helped define human rights—set against the backdrop of wartime diplomacy, Cold War tensions, and the San Francisco Conference, where the UN Charter was signed.

Relationships between countries have become more peaceful since the rules-based order was established

Our World in Data monitors bilateral relationships on a spectrum from open rivalry to "positive peace"—deep cooperation and mutual protection. In 1945, no countries had highly cooperative security relationships. Today, nearly a fifth do.

Ukraine has received over $300B in Western military and financial aid

Although not a member of NATO, Ukraine has received substantial support from Western nations, primarily the United States and the European Union, totaling more than $300B in military, financial, and humanitarian assistance.

Congress has formally declared war 11 times across five conflicts, the last in 1942

The five declared wars were the War of 1812, the Mexican-American War, the Spanish-American War, World War I, and World War II. Every major American military conflict since Korea, Vietnam, Iraq, and Afghanistan has been fought without a formal declaration.

The Concert of Europe was an earlier attempt to manage great power relations through shared rules

After the Napoleonic wars, European powers established a system of regular consultation to manage conflicts and maintain the balance of power. It offered relative stability for nearly a century before deteriorating.

NASA was created by Congress in 1958

Created by Congress under the National Aeronautics and Space Act, NASA officially began in 1958, building on earlier aviation research and positioning the US to compete in the Space Race and lead global space exploration.

The Marshall Plan aimed to rebuild Europe and limit Soviet influence

Launched in 1948, the Marshall Plan provided over $12B (roughly $150B today) in US aid to help rebuild Western Europe. While framed as economic recovery, it also served as a Cold War tool—tying countries to the US and excluding the Soviet bloc.

The Arab League has 22 members and very little enforcement power

It was founded in Cairo in 1945 and spans 22 nations across the Middle East and North Africa, ostensibly to coordinate policy on economics, culture, and defense. Its charter says any resolution only binds states that voted for them, rendering most of them toothless.

The US and allies invaded Iraq based on flawed intelligence about potential weapons of mass destruction.

The Non‑Proliferation Treaty was designed to prevent new states from developing nuclear bombs

The Treaty on the Non‑Proliferation of Nuclear Weapons (created in 1968, effective 1970) binds non-nuclear states to forgo nuclear weapons and commits nuclear powers to share peaceful technology and pursue disarmament—forming the core of the global non-proliferation regime.

The global nuclear arms regime has slowly eroded over the past few decades

Both Russia and the United States have withdrawn from key Cold War-era arms-control pacts. Russia's 2022 invasion of Ukraine marked a turning point, as it suspended its participation in inspections and data-sharing agreements.

Churchill’s 1946 ‘Iron Curtain’ speech warned of growing Soviet domination

In a 1946 speech, Winston Churchill declared that an “Iron Curtain” had descended across Europe—dividing East from West. The address marked one of the first public acknowledgments of the emerging Cold War and coined the term that would define the conflict.

National Hockey League, explained

Founded in 1917, the NHL started with four Canadian teams and now spans 32 franchises across North America. Its iconic Stanley Cup, first awarded in 1893, remains a unique prize, with winners' names hand-engraved each year. The league generates billions in annual revenue, aided by key expansions, lucrative TV deals, and global fan engagement. While player safety and labor disputes have posed challenges, the NHL remains a cornerstone of professional sports, offering an 82-game season culminating in the fiercely contested Stanley Cup Final.