Nuclear Weapons

They’re the most dangerous invention the world has ever seen. Can we prevent them from being used again?

What we’re facing

When the United States dropped the first atomic bomb on Hiroshima, the destruction was unlike anything experienced before. Tens of thousands of people died instantly. An entire city was destroyed in the flash of a single bomb.

Today, some 9,000 nuclear weapons remain in the world’s arsenals—with over 90 percent owned by the United States and Russia. Both countries are actively planning to build new weapons, sparking a 21st century arms race and increasing the risk of nuclear war.

Meanwhile, many of the Cold War’s most absurd and dangerous nuclear policies remain unchanged. In the United States, the president can order the launch of nuclear weapons without consulting anyone. And US policy allows it to use nuclear weapons first in a non-nuclear conflict with Russia, China, or North Korea—likely starting a nuclear war.

These policies and plans threaten the world in very real ways, and they need to change. You can help.

All Things Nuclear

All Things Nuclear

All Things Nuclear

Read More

Reducing the Risk of Nuclear War

Reducing the Risk of Nuclear War

Taking Nuclear Weapons Off High-Alert

Accidental nuclear war is more often portrayed as the subject of science fiction, not an actual possibility.

But despite the Cold War ending decades ago, the United States and Russia still keep hundreds of nuclear weapons on high alert, ready to launch. Also known as “hair-trigger alert,” this rapid launch option significantly raises the risk of an accidental, unauthorized, or mistaken nuclear attack, with no appreciable benefits to national security.

On its surface, the system is simple: if we detect and verify a nuclear attack, we’ll launch our own missiles before they’re destroyed. But the process must occur within minutes, and relies heavily on error-prone radar, satellite, and human communication systems, all of which are susceptible to false alarms and, potentially, cyberattack. And because the timeframe is so short, the military depends on scripted nuclear launch procedures that are routinely rehearsed, biasing the process toward a decision to launch—especially in times of crisis.

From faulty computer chips to simple human mistakes, dozens of near misses and safety accidents illustrate these and other shortcomings. No single incident has caused an accidental, unauthorized, or mistaken launch yet—but the probability is not zero. The more incidents that occur, the greater the chance that, due to confusion and an unforeseen confluence of events, one of them will lead to disaster.

Arguments for retaining high alert

Because land-based nuclear missiles are stored at known locations, they are vulnerable to attack. Hair-trigger alert was originally intended to ensure that, were the missiles targeted, they could be launched in retaliation before being destroyed. Yet the United States’ retaliatory capabilities are already ensured by hundreds of nuclear weapons stored on submarines, which can’t be targeted. As a deterrent, the high alert status of U.S. land-based missiles is therefore irrelevant.

Some experts argue that de-alerting could lead to a “re-alerting race” during a future crisis, in which two quarreling sides raise their alert levels in a high-stakes game of “tit for tat,” exacerbating tensions. But this is premised on the notion that rapid-launch missiles are needed for deterrence, which is untrue.

Others argue that hair-trigger alert is needed for “extended deterrence,” ie, the assurance to others—particularly Japan—that the United States will provide nuclear retaliation on their behalf. But extended deterrence depends on the U.S.’ willingness to retaliate, not the speed of its decision. Numerous Japanese leaders have, in fact, expressed enthusiasm for U.S. de-alerting.

How to de-alert nuclear missiles

The U.S. should eliminate options for quickly launching missiles on warning of attack, and take its missiles off hair-trigger alert. At present, land-based intercontinental ballistic missiles (ICBMs) in the United States are stored in underground siloes and controlled by nearby launch centers. Removing them from hair-trigger alert could be as simple as manually activating a safety switch that prevents the missile from being launched (these switches already exist and are used by maintenance crews). When the next false alarm occurs, leaders would then not be under the same pressure to launch, eliminating the risk of a mistaken launch, and reducing the risk of an accidental or unauthorized launch.

The time for change is now. Despite promises as a candidate and early in his first-term, President Obama’s administration decided not to end hair-trigger alert during its 2010 Nuclear Posture Review. The security environment has, however, changed. Tensions between Russia and the United States are higher than they have been in decades, and China is considering placing its nuclear arsenal on high alert for the first time, citing U.S. security capabilities. In a cautionary 2015 address, former U.S. Secretary of Defense William Perry declared: “today we now face the kind of dangers of a nuclear event like we had during the Cold War, an accidental war.”

Taking nuclear weapons of hair-trigger alert would be a strong first step toward ensuring nuclear war remains the stuff of fiction.

In this report

Close Calls with Nuclear Weapons

Close calls have nearly led to the launch of nuclear weapons—and the risk is still there. Learn about past incidents and current issues here. Report

Leaders Urge Taking Weapons Off Hair-Trigger Alert

A surprising number of high-level politicians and generals have called for an end to hair-trigger alert.

Downloads

Full report

The US Nuclear Arsenal

The US Nuclear Arsenal

Here’s every nuclear weapon in the US arsenal.

Each point represents a nuclear weapon—the most destructive device on Earth. The US nuclear arsenal includes over 4,600 weapons.

Scroll through the interactive feature to get a sense for just how large the US nuclear arsenal really is…

How Do Nuclear Weapons Work?

How Do Nuclear Weapons Work?

At the center of every atom is a nucleus. Breaking that nucleus apart—or combining two nuclei together—can release large amounts of energy. Nuclear weapons use that energy to create an explosion.

Modern nuclear weapons work by combining chemical explosives, nuclear fission, and nuclear fusion. The explosives compress nuclear material, causing fission; the fission releases massive amounts of energy in the form of X-rays, which create the high temperature and pressure needed to ignite fusion.

Take a deep dive into nuclear weapons with the rest of this post, which includes accessible descriptions of fission and fusion, how nuclear weapons work, nuclear fuel, warheads in-depth, and more.

Voters Strongly Support a “No First Use” Nuclear Policy

Voters Strongly Support a “No First Use” Nuclear Policy

The President should declare that the United States will never start a nuclear war.

The choice to use nuclear weapons is the most momentous decision a president could ever take, with the fate of millions at stake. Just one bomb could kill hundreds of thousands of people, while a full-scale exchange could end life as we know it. Currently, the United States reserves the right to use nuclear weapons first in a conflict, and the authority to launch nuclear weapons lies solely with the president.

Adoption of a “No First Use” (NFU) policy means the United States would commit to never initiating a nuclear conflict. A NFU policy would reduce the risk of other countries using nuclear weapons against the United States and contribute to global stability through leading by example.

UCS commissioned polls in several states and has found strong support for a US NFU policy, and even stronger support for the idea that the presidential candidates should be talking about nuclear weapons issues on the campaign trail.

New Hampshire (University of New Hampshire poll, March 2019)
Residents who believe the United States should never use nuclear weapons first: 73%
Residents who believe it is important for presidential candidates to give their views on nuclear weapons: 84%

Iowa (Zogby Analytics poll, April 2019)
Residents who believe the United States should never use nuclear weapons first: 57%
Residents who believe it is important for presidential candidates to give their views on nuclear weapons: 82%

Michigan (Zogby Analytics poll, July 2019)
Residents who believe the United States should never use nuclear weapons first: 67%
Residents who believe it is important for presidential candidates to give their views on nuclear weapons: 82%

Ohio (Zogby Analytics poll, October 2019)
Residents who believe the United States should never use nuclear weapons first: 65%
Residents who believe it is important for presidential candidates to give their views on nuclear weapons: 84%

Georgia (Zogby Analytics poll, October 2019)
Residents who believe the United States should never use nuclear weapons first: 61%
Residents who believe it is important for presidential candidates to give their views on nuclear weapons: 86%

South Carolina (Zogby Analytics poll, February 2020)
Residents who believe the United States should never use nuclear weapons first: 62%
Residents who believe it is important for presidential candidates to give their views on nuclear weapons: 83%

Downloads

Georgia fact sheet

Iowa fact sheet

Michigan fact sheet

New Hampshire fact sheet

Ohio fact sheet

South Carolina fact sheet

US Missile Defense

US Missile Defense

Unproven, unaccountable, and unhelpful for reducing the nuclear threat.

Six hours north of Anchorage, Alaska, lies a sprawling, snow-covered military base called Fort Greeley. Three thousand miles to its south, outside Lompoc, California, is another major installation—Vandenberg Air Force Base.

The two bases are linked by a unique security objective: to destroy nuclear-tipped missiles bound for the United States, should they ever be launched from North Korea or another hostile state.

Unfortunately, the system creates far more problems than it solves, and it likely wouldn’t work in the event of an actual attack—a practical reality that money and research won’t fix.

Learn more about how missile defense works, oversight and accountability, and space-based missile defense.

Preventing Nuclear War

Preventing Nuclear War

It shouldn’t be easy to start a nuclear war. Campaign contact

By Madison Arnold-Scerbo, Outreach Associate

For more than 70 years, the world has faced the very real threat of nuclear war.

What if we lived without that danger hanging over our heads?

That’s what we’re fighting for, across the country and in the hallways of DC—and that’s why we need you.

Call for investments in public health & security, not nuclear weapons.

Nuclear war is a real and growing threat. The United States and Russia have left critical agreements and treaties, while actively planning to add new types of weapons to their arsenals.

Meanwhile, US nuclear policy remains rooted in the Cold War, increasing the risk that nuclear weapons could be used again.

It doesn’t have to be this way. With the right policy changes and a commitment to diplomacy, the United States can be a leader in reducing the nuclear threat—and you can help.

What we’re doing

  1. Engaging & educating presidential candidates,
  2. Pressuring Congress to support change,
  3. Holding the White House accountable through independent research and analysis,
  4. Increasing public demand for changing nuclear weapon policies.

What You Can Do

Space-based Missile Defense

Space-based Missile Defense

It may sound like a good idea. It really isn’t. In 1983, President Ronald Reagan proposed a military system, later dubbed “Star Wars,” that promised to protect the United States from nuclear attack. The basic idea was to use weapons based in space to knock down incoming intercontinental ballistic missiles (ICBMs).

Space-based Missile Defense: Not a Good Idea

Politicians have called for “space-based missile defense” for years. Unfortunately, it’s not a very good idea.

Reagan’s plan didn’t materialize, but the idea never went away. In 2018—against the Department of Defense’s wishes—Congress passed a bill calling for the Pentagon to start building space-based interceptors.

Unfortunately, it’s a terrible plan. Space-based missile defense is an ineffectual defense at best, and a very dangerous provocation at worst.

Understanding why space-based missile defense is a bad idea requires basic knowledge of how it works—and what it can and can’t do.

Click here for more information and interactive features about what missile defense systems are and why they’re prone to failure.

Security and Arms Control Webinars

Security and Arms Control Webinars

The Summer Symposium hosts security experts from across the globe, speaking on technical issues related to global security.

Published Mar 28, 2014 Updated Feb 9, 2017

Trying to join a webinar? View instructions here.

This page contains abstracts and archived recordings of lectures on global security issues, including missile defense, North Korea and Iran, nonproliferation, and US nuclear weapons. The lectures come from webinars, presented on Youtube, or in either shockwave (.swf) or video files that can be viewed in a web browser.

For more information, please contact:

  • George Lewis at Cornell University, gnl3 [at] cornell.edu
  • David Wright with the Union of Concerned Scientists, dwright [at] ucsusa.org

Note: As of January 1, 2017, webinars and lectures from this series will be posted exclusively on Youtube, accessible here. Older presentations can still be found here.