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

Chart decades of US–Russia nuclear diplomacy

Over the Cold War and into the 21st century, US and Soviet/Russian leaders repeatedly agreed to cap arsenals, curb missile deployment, and share ongoing inspections—creating decades of transparency. But in recent years, strained tensions have led to the expiration of arms treaties.

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 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.

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.

Russia's invasion of Ukraine has destabilized safety and oversight at Chernobyl

Russian forces cut power and disabled monitoring of the decommissioned nuclear power plant in 2022, endangering operators at Chernobyl. In February 2025, a Russian drone struck the confinement structure—part of broader efforts to pressure Ukraine's energy infrastructure—punching a hole in the containment shell.

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.

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.

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.

Many countries remained neutral after Russia's invasion of Ukraine

Following Russia's 2022 invasion of Ukraine, few nations outside the West imposed sanctions on Moscow. Major powers such as China, India, Brazil, and Turkey remained neutral, underscoring global divisions over how to confront Russian aggression.

Russia's invasion of Ukraine accelerated fractures in the rules-based international order

This piece examines how the Ukraine conflict intensified underlying divisions in the global order—between Western democracies and the Global South, and between rule-of-law norms and great-power politics.

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.

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 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.

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.

A deep dive on the weapons being used by both sides

From ballistic missiles to armed drones, Russia’s invasion of Ukraine is proving the devastating power of modern weaponry. This infographic illustrates and explains the uses and effects of the weapons of choice for both sides of the conflict. Tactics are also explored in regards to their efficacy and consequences, with expert commentary added.

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.

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

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.

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.

Chernobyl pushed the world to create rapid-alert systems for nuclear accidents

In the aftermath of the disaster, nations adopted new agreements requiring immediate international notification of nuclear accidents. They coordinated emergency assistance—efforts led by the International Atomic Energy Agency to prevent future disasters from being concealed when radiation emergencies occur.

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

Testing assumptions about the war in Ukraine, one year later

Two years ago, policymakers in Washington made multiple predictions about the course of the war between Russia and Ukraine. One year later this site revisited several common assumptions about the war—for example, that Russia would swiftly defeat Ukraine—and asks several experts if they came true, or not. But things can always change.

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.

After it was banned from Eurovision, Russia resurrected its Cold War-era version

Russia was barred from the Eurovision Song Contest following its 2022 invasion of Ukraine. In 2025, President Vladimir Putin announced the revival of Intervision, a similarly structured song contest that the Soviet Union had organized throughout the Cold War.

View a list of the worst nuclear meltdowns before 2013

Nuclear meltdowns occur when a reactor overheats and radioactive materials leach into the surrounding environment. While rare, the reasons for each occurrence—as detailed in this piece—can help establish new safety protocols for future reactors.

The Minsk peace accords failed to end fighting in eastern Ukraine in the mid-2010s

The Minsk Agreements of 2014 and 2015 sought to halt the war in eastern Ukraine through ceasefires and political reforms, but repeated violations left the accords unenforced and the conflict unresolved.

The United States has had a tumultuous relationship with Cuba since its 1959 revolution, highlighted by a nuclear crisis and a decades-long trade embargo.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

The United States is one of only around two dozen countries with a fully federal system of government, in which power is divided between national and state governments.

The power and influence of the American presidency have expanded significantly over time—far beyond what the founders envisioned.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

Before humans, the Soviet Union and the United States sent animals—including apes, dogs, and cats—to space during the Space Race.

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

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

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

11 people died from firework injuries in the US in 2024.

Roughly 43 million US borrowers owe roughly $1.7T in student debt, the second-largest source of consumer debt behind mortgages.

The American Society of Civil Engineers' infrastructure report card gave the US a C in 2025, its highest grade since the project launched in 1998.

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.'

In 2019, a laptop loaded with six of the worst malware in history and described as 'an exhibit of historical weaponry' sold for $1.3M.

The original copy of the Declaration of Independence is not a pristine document, and even features a smudged anonymous handprint in the bottom left corner.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

See the 25 of the best photos of auroras from around the world.

Poison ivy will likely become both larger and more resilient due to climate change.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

The distributor behind 'Rocky Horror' pulled the film from its scheduled national release, believing it would be a failure, though it eventually amassed a dedicated fanbase through midnight showings, a trend that continues over 50 years later.

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

In preparation for this weekend's Eurovision finale, which is something like the World Cup of pop music, here's a young Céline Dion performing (for Switzerland?) at the 1988 competition.