Since World War II, US and Soviet/Russian leaders have repeatedly agreed to arms control treaties, though strained tensions have led to the expiration of agreements in recent years.

The last remaining US-Russia nuclear arms treaty expired in February 2026

The New START treaty, which capped US and Russian strategic warheads at 1,550 each, expired on Feb. 5, 2026. Without formal limits, fears of a renewed arms race are rising, as both nations could deploy more weapons while follow-on talks continue.

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Both Russia and the United States have withdrawn from key Cold War-era arms-control pacts.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.

Some scientists propose AI-powered satellites to monitor nuclear weapons in place of arms control treaties

With the New START treaty expired, researchers at the Federation of American Scientists have proposed using satellites and AI to remotely verify nuclear arsenals—replacing the onsite inspections that once built trust between the US and Russia during the Cold War.

See how global nuclear arsenals surged—then shrank—by country since 1945

Worldwide nuclear stockpiles peaked at over 60,000 warheads in the mid‑1980s during the US-Soviet arms race. Today, about nine nations collectively maintain roughly 12,000 warheads, with Russia and the US still holding the majority.

Four Cold War hawks warn: Nuclear weapons still threaten the world

Despite the Cold War's end, the US and Russia still hold 95% of the world's nuclear weapons—many on hair-trigger alert. In this 2010 documentary, top former officials urge urgent action to reduce and eliminate the threat.

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 Soviet Union’s surprising first atomic test ended the US nuclear monopoly

In 1949, the USSR successfully tested its first atomic bomb—ending the US monopoly on nuclear weapons and sparking an arms race that would define the Cold War.

The failed Bay of Pigs invasion led to the Cuban Missile Crisis, which brought the world to the brink of nuclear annihilation

Moscow's decision to deploy nuclear missiles in Cuba—just 90 miles from the US—pushed the world to the brink of nuclear war. To prevent future crises, both sides later set up a direct hotline and boosted arms-control diplomacy

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."

Nearly 90% of the world's 12,321 nuclear warheads are held by Russia and the United States.

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.

Presidents now rely on executive agreements instead of formal treaties

Formal treaties—requiring two-thirds Senate approval—have become rare in American foreign policy. Modern presidents increasingly use executive agreements, which don't need congressional consent, allowing faster diplomacy but reducing legislative oversight and transparency.

See a timeline of the tumultuous relationship between Cuba and the US since 1959

Only 90 miles separate Cuba from the US, yet Cold War hostility froze relations for decades. This timeline traces six decades of tension, from revolution and missile crisis to renewed hardline US policies reintroduced in 2025

The space race ended with a handshake in orbit in 1975

On July 17, 1975, American and Soviet astronauts docked their spacecraft during the Apollo–Soyuz mission, symbolically ending the space race and marking the first joint spaceflight between Cold War rivals.

Ukraine once had the third-largest nuclear arsenal—and gave them all up by 1996

After the rapid collapse of the Soviet Union, Ukraine was left with over 1,700 nuclear warheads positioned throughout its territory. A massive global effort ensued, led by the United States, to return these and other nuclear weapons in former Soviet allied states to Russia.

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.

US–Soviet hostility began long before the Cold War

US–Soviet tensions began decades before WWII. After the 1917 revolution, the US refused to recognize the Bolshevik regime and even sent troops to fight against it.

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.

Explore the fraught relations between the United States and Cuba since 1959

From the Cuban Missile Crisis and decades of economic embargo to President Obama's normalization efforts and President Trump's reversion to "maximum pressure," US-Cuba relations have fluctuated between hostility and fleeting diplomacy since Fidel Castro's 1959 revolution.

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 US and the USSR each boycotted Olympic Games during the Cold War

The US led a boycott of the 1980 Moscow Olympics over the Soviet invasion of Afghanistan. In retaliation, the USSR and its allies skipped the 1984 Los Angeles Games.

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.

An interactive visualization tracking 25 years of US-North Korea nuclear negotiations

From 1990 to 2017, the United States and North Korea engaged in a complex series of bilateral and multilateral negotiations. This interactive page, compiled by CSIS Beyond Parallel, displays a record of provocations and negotiations between the two...

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

Economic stagnation and the arms race pushed the USSR toward collapse

By the 1980s, chronic economic stagnation and soaring military costs forced Gorbachev to launch sweeping reforms—perestroika and glasnost—to revive the Soviet system. Instead, openness fueled independence movements across the republics, accelerating the regime’s rapid downfall.

Roosevelt formally recognized the Soviet Union in 1933

In 1933, President Franklin D. Roosevelt formally recognized the Soviet Union—ending 16 years of nonrecognition and aiming to improve trade and stabilize relations amid growing global instability.

A primer on the president's nuclear football

During the Cold War, the United States and the USSR were forced to prepare for a nuclear strike at a moment's notice, leading to a new innovation: the so-called "football" (known as the chemodanchik in Russia), a bag containing nuclear strike plans, authentication codes, and likely a communication device, which attended the country's leader wherever they went. This easy-to-read piece breaks down the history and lore around the high-stakes quirk in nuclear governance.

US–Cuba contentious relations began long before the Cold War

Long before the revolution and missile crisis, US involvement in Cuba stretched back over 150 years—rooted in slavery, sugar, and shifting imperial ambitions. This short video traces how cycles of intervention and neglect shaped the island’s modern history.

During the Cold War, the rules-based order was largely limited to the West

The Soviet Union and its allies operated outside the Bretton Woods institutions, meaning the postwar liberal order functioned as a regional rather than a truly global system. This changed with the USSR's collapse in 1991.

The origin of atmospheric science while testing nuclear weapons during the Cold War

The arms race between the US and the Soviet Union saw both countries stockpiling and detonating hundreds of bombs underground, underwater, and in the atmosphere. To better predict where nuclear fallout would travel after these tests, scientists developed models that would serve as a foundation for those used to explain atmospheric circulation.

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.

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.

A timeline of Russia-North Korea relations

North Korea and Russia have often had aligned interests, yet their relationship has experienced many highs and lows. Al Jazeera’s explainer outlines the key events defining Russia-North Korea relations. Russia and North Korea were allies during...

Because the Korean War ended with an armistice rather than a peace treaty, North and South Korea are technically still at war.

Experts argue that nuclear war is more likely than is commonly believed

The podcast highlights that many of the world's roughly 12,000 nuclear weapons—capable of triggering global collapse and nuclear winter—remain on high alert. Experts warn that this status, combined with limited public awareness, makes nuclear war disturbingly plausible.

Cold War rivalries fueled fierce competition in international sports

From Olympic medal counts to hockey showdowns, the US and USSR used sports to showcase ideological superiority. Athletic victories were framed as proof that each system—capitalist or communist—produced stronger, more disciplined citizens.

The US and the USSR backed opposing sides in dozens of proxy wars during the Cold War

To avoid direct confrontation, the superpowers supported rival factions in conflicts around the world—including in Korea, Vietnam, Angola, and Afghanistan.