Primer on Nuclear Declaration

The devastating legacy of nuclear testing still lingers in human health, in toxic landscapes, and in global tensions. Since the first nuclear test on July 16th, 1945, more than 2000 nuclear explosive tests have been conducted around the world. Even after most nuclear countries paused testing, old test sites remain radioactive and uninhabitable. The destructive force of the 529 atmospheric nuclear tests, not counting the thousands conducted underground, equalled 29,000 Hiroshima bombs. Fallout from the tests contaminated the air, soil, and water, with little or no thought given to the local communities and ecosystems that surrounded test sites. Beyond the radioactive consequences, nuclear tests are considered provocative by international observers and can fracture the fragile stability between nuclear states. No one is comforted when a country proves that its nuclear weapons work. This is an era we cannot afford to return to. To help prevent its resurgence, the Assembly calls for states to recommit to a moratorium on nuclear explosive testing.

North Korea is the only country that has conducted a nuclear test this century, its most recent in 2017. Even then, North Korea tested its weapon underground, where the atmospheric effects could be somewhat controlled. However, there has recently been renewed interest in resuming nuclear testing among nuclear weapons states, including the United States, China, and Russia. Nuclear testing is an opportunity to test whether new technology functions as intended. Since the U.S., China, and Russia are modernizing their arsenals, they may be incentivized to assess their new technology and demonstrate their capabilities to their rivals. Nuclear testing could potentially prove and improve the performance of devastating weapons—and if any one state were to begin testing, others are likely to follow.

With one test, we could unravel and undermine the decades of diplomacy that brought us to this point. Instead, we should take advantage of this opportunity to affirm the importance of international cooperation. For this reason, the Assembly asks states to secure the prompt entry into force of the Comprehensive Nuclear Test Ban Treaty (CTBT). The treaty bans all nuclear tests, whether for military or civilian purposes. To enter a treaty into force means that the treaty becomes legally binding and fully effective for the participating states. To trigger entry into force, the treaty must be ratified by all signatory states. Today, China, Pakistan, Russia, the DPRK, Egypt, the U.S., India, Iran, and Israel have not ratified the treaty, preventing it from entry into force. By entering the CTBT into force, states affirm that our goal is to preserve nonproliferation efforts rather than enter another age of reckless nuclear testing.

Having more nuclear weapons than necessary to ensure deterrence does not inherently enhance security; it can increase the risk of miscalculation, preemption, and escalation. To address this, the Assembly also focused on potential measures and agreements that would help maintain strategic stability. Strategic stability can be defined as a condition where no state has the incentive to carry out a nuclear strike first. Arms control agreements can help uphold strategic stability since countries aren’t actively working to exploit their enemy’s weaknesses. Right now, however, arms control treaties are expiring and countries seem hesitant to engage in substantive discussion. Without limitations that are agreed upon by nuclear states, there is nothing stopping us from entering another arms race with spiraling weapon counts and devastating novel weapons. As President Kennedy said, “men may no longer pretend that the quest for disarmament is a sign of weakness—for in a spiraling arms race, a nation’s security may well be shrinking even as its arms increase.” In an unchecked arms race, “every man, woman and child lives under a nuclear sword of Damocles.”

The New Strategic Arms Reduction Treaty (New START) between the United States and Russia will expire in February 2026. When New START expires, the U.S. and Russia will, for the first time in decades, not be constrained by an arms control treaty. The Assembly calls for both nations to immediately enter into negotiations into a successor to the treaty and to expand negotiations so that the treaty addresses their full nuclear arsenals. Currently, New STARTonly applies to certain types of nuclear weapons systems It does not cover tactical nuclear weapons (or low-yield nukes that could potentially be deployed on the battlefield), non-deployed strategic delivery systems, or missile defense. All of these technologies are currently being heavily invested in by the U.S. and Russia, and advancements in these technologies could disrupt the fragile nuclear peace between them. In the meantime, both nations should abide by the limits of New START even after it expires rather than engaging in a new arms race. 

Moreover, it is clear that China is rapidly expanding their arsenal, which is seen as escalatory and threatening by many of its adversaries. Currently, China has resisted engaging in arms control dialogue with the U.S and Russia because it still has a smaller arsenal in comparison. Without any transparency, however, China’s build up and modernization efforts may encourage regional and global competitors to follow suit. India, for example, may accelerate its nuclear weapons program to develop an effective counter for China’s much larger stockpile. To ensure that we do not enter another global scramble for nuclear weapons, the Assembly calls on China to enter substantive and sustained discussions on their rapidly expanding arsenal and consider risk reduction measures, such as increased transparency, that would mitigate the escalatory nature of their build-up.

Finally, conversations about nuclear buildup and arms control are not only relevant to states with large arsenals—they are essential for all nations concerned with global security. Conflict between states with smaller arsenals, such as India and Pakistan, can quickly become catastrophic. All nuclear weapons states must engage in discussions with each other through both established forums and new channels. A world without an arms race is in all of our interests. But if countries are not willing to engage candidly and consistently, then progress is impossible.

Bringing artificial intelligence into the nuclear chain risks trading human judgment for machine error. The integration of new technology, such as artificial intelligence (AI), into nuclear systems carries serious risks. While AI may offer advantages in safety, speed, and data processing, it is also fallible: algorithms can make errors, misunderstand context, or act unpredictably when placed in high-stakes, real-world conditions. The Assembly first calls for states to engage in cooperative dialogue on the implications of these technologies to ensure that they are not recklessly and short-sightedly interwoven into critical nuclear systems. International cooperation and consensus is necessary. If countries are operating off of different understandings of AI and the risks it poses, then even if one government is acting safely, there is no guarantee that all nuclear states are. Furthermore, AI evolves very quickly, and treaties will not be able to keep up. We need more than one document that is meant to last decades when AI outpaces itself within weeks. As such, sustained international dialogue is necessary to introduce and update safeguards. Even if AI can help improve a country’s offensive capabilities, it serves no state’s security if algorithmic error can lead to apocalyptic consequences. 

Beyond enhanced international dialogue, the Assembly called for enhanced human oversight over nuclear command and control systems. While the U.S. has led discussion on maintaining human control in decision-making, with China affirming this principle last year, it is unclear whether other states accept or believe in the dangers of integrating AI into their systems. Nuclear-armed states must ensure that no critical decision, especially one involving the use of nuclear weapons, is made without meaningful human involvement. This includes lengthening decision-making timelines so that leaders have time to verify incoming information and carefully weigh any use-of-force decision. Computer error has almost started nuclear wars. In 1983, the Soviet early warning system mistook sunlight reflecting on clouds as an incoming ballistic missile attack. Defying protocol, Soviet military officer Stanislaw Petrov decided to trust his judgment and chose not to immediately launch Soviet missiles in retaliation. Even if technology has improved since 1983, decisions with grave humanitarian consequences must be taken by humans, not computers and code.

At the same time, the Assembly acknowledged that human judgment is also fallible. To reduce the risks of impulsive or mistaken decisions by any one individual, the Assembly urged all nuclear states to adopt a “two-person rule.” This rule would require at least two people to be involved in any decision regarding the use of nuclear weapons, adding a layer of accountability and helping prevent catastrophic errors. Right now, several states leave the decision to use nuclear weapons up to one person, which is known as sole authority. The decision to use weapons of mass destruction—and thereby irrevocably fracture global stability—often lies in the hands of one man. As artificial intelligence accelerates decision-making timelines and introduces unprecedented forms of informational uncertainty, maintaining such concentrated control is increasingly perilous.

Since the Cold War, we have imagined massive interceptors protecting our cities and skies from oncoming missile attacks; however, accurate missile defense remains impossible to replicate in reality. Missile defense refers to a system, weapon, or technology designed to detect, track, intercept, and destroy incoming missiles before they reach their intended targets. During the Cold War, the U.S. and the Soviet Union worried that ballistic missile defense could undermine deterrence and prompt an uncontrollable arms race. For this reason, both nations signed the 1972 Anti-Ballistic Missile Treaty which restricted each side to 100 strategic missile defense interceptors at one site. Such an amount would not make either country invulnerable to an oncoming nuclear strike. In 2002, the U.S. withdrew from the ABM treaty to develop missile defense against possible ‘rogue state’ ballistic missile attacks. The treaty is no longer in effect.

At first glance, missile defense, which could protect cities from nuclear catastrophe, might seem stabilizing. However, nuclear deterrence works because both sides know that if they launch a nuclear attack, they will be hit back just as hard. This fear of retaliation is what keeps countries from using nuclear weapons—and missile defense can weaken that fear. If one country thinks it can protect itself after launching a nuclear strike, it may be more willing to strike first. Building up missile defense systems can look like an attempt to gain an advantage, which may push other countries to do the same. Furthermore, states will want to be able to overwhelm the missile defense systems of their adversaries by building more and better offensive weapons. Massive investments in strategic missile defense can undermine the credibility of deterrence and trigger arms races, as states work to ensure their arsenals remain viable. The world becomes less stable, not more.

The Assembly therefore urges the United States, Russia, and China to recognize the tight interconnection between offensive and defensive capabilities. The Assembly calls on these three nuclear powers to forgo such large-scale investments and to approach missile defense with transparency and restraint, preserving the balance that strategic stability requires.

The term space weapon conjures up thoughts of space lasers or the Death Star from Star Wars. Reality isn’t very far off. A nuclear weapon in space, with a single detonation, could disable thousands of satellites—systems we depend on. Navigation, communications, and financial systems would all go down within minutes. In this recommendation, the Assembly turned to the risks posed by the militarization of outer space. The 1967 Outer Space Treaty prohibits the placement of nuclear weapons or other weapons of mass destruction in orbit or on celestial bodies like the Moon. However, new technologies and military developments have raised concerns that some states may be considering space-based weapons or missile defense systems with nuclear capabilities. Placing nuclear weapons in space would be extremely destabilizing. Our nuclear command and control relies on satellites we would no longer be able to access. Furthermore, it could provoke a dangerous arms race and increase the risk of accidental or intentional escalation beyond Earth’s atmosphere which would have devastating environmental and atmospheric consequences. At the same time, space militarization is not tomorrow’s problem. Already, states utilize satellites for military purposes, and states build anti-satellite weapons to counter them. 

The Assembly therefore urges all states to recommit to the Outer Space Treaty and work to modernize the agreement to address today’s challenges, including anti-satellite weapons, dual-use technologies, and space-based surveillance systems.

We have come terrifyingly close to nuclear disaster, and we have survived through sheer chance. We cannot rely on chance forever. A nuclear close call refers to a situation in which the detonation of a nuclear weapon, whether intentional or accidental, was narrowly avoided. Many nuclear command and control systems are designed to prioritize speed, but this emphasis on rapid response often comes at the cost of time to verify information or prevent miscalculation. As the Declaration warns, “time and the law of probability are not on our side.” It is critical that nuclear command and control systems are carefully designed to minimize the risk of error and ensure decisions are made with clarity and caution.

The Assembly recommends that nuclear armed states expand secure communication lines that can be utilized during a crisis to ensure that confusion does not evolve into calamity. A “hotline” provides a way for world leaders to talk to ask each other if something was an intended attack or just an accident. In the depths of a crisis, when it might be impossible to meet in person for full-fledged negotiations, leaders can still take a phone call. Reliable, rapid, and confidential methods of communication can prevent escalation in a crisis and provide pathways to limiting or terminating war. The Assembly calls on all nuclear armed states to implement similar measures. Talking to each other before a crisis hits makes it much more likely we’ll avoid disaster when it does. The more countries are in constant, honest conversation about how to prevent and manage nuclear emergencies, the better chance we have of pulling back from the edge when everything’s on the line.

Nuclear proliferation—the spread of nuclear weapons to additional states—poses one of the greatest threats to global stability. As more countries inch closer to developing nuclear capabilities, the risk of miscalculation, accidental launch, or regional conflict escalating into nuclear war rises dramatically. States with high nuclear latency, those that could build a weapon quickly, add to this danger by shortening the time for diplomacy to work in a crisis and increasing uncertainty among rivals. Even if a state doesn’t yet possess a nuclear weapon, its rivals may still consider launching a preemptive strike to stop it from becoming a nuclear-armed threat, especially if both states are already locked into a conflict. This threat of preemption encourages states to attain the weapon even faster. Right now, as international alliances shift and trust erodes, many countries are considering building nuclear weapons.  Although these countries aim to bolster their security, when nuclear weapons spread, so do the chances of catastrophe.

In this context, the Assembly reaffirmed the importance of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which entered into force in 1970. The NPT rests on three key pillars: preventing the spread of nuclear weapons and weapons technology (or nonproliferation), pursuing nuclear disarmament, and promoting the peaceful use of nuclear energy. It remains the most widely adopted nuclear agreement, with 191 signatories, including the five recognized nuclear-weapon states. While the treaty has helped slow the pace of nuclear proliferation, it has been under increasing strain due to stalled progress on disarmament, modernization of nuclear arsenals, and regional tensions. In this recommendation, the Assembly calls on all states to publicly recommit to the full set of obligations and objectives laid out in the treaty. This includes reaffirming disarmament commitments and rejecting nuclear proliferation by any state—including allies. 

To preserve the integrity and future of the NPT, the Assembly also calls on states to enhance their political, diplomatic, and financial support for multilateral nuclear diplomacy and the institutions that uphold it, such as the International Atomic Energy Agency (IAEA) and the NPT Review Conference process. These forums serve as essential spaces for transparency, cooperation, and accountability. Without strong international backing, the NPT and nonproliferation efforts will be weakened—undermining global norms and increasing the risk of unchecked nuclear competition.

The initial explosion of a nuclear exchange would kill millions. However, the climatic consequences of a nuclear strike extend far beyond its detonation, resulting in the deaths of billions. Nuclear winter refers to a global climate catastrophe that could follow the large-scale use of nuclear weapons. When nuclear weapons detonate in fuel-rich areas—such as major cities or industrial zones—the resulting firestorms can send massive amounts of smoke, soot, and debris into the upper atmosphere. This material would block sunlight, sharply cooling the planet’s surface and disrupting weather systems.

The ramifications would be devastating. Global temperatures could drop significantly, and growing seasons would shorten or collapse altogether, triggering widespread crop failures and food shortages lasting at least a decade. Scientists estimate that a full-scale nuclear war between the United States and Russia could kill over 5 billion people within the first few years, mostly from starvation. In both countries, summers could fall below freezing, and access to food would be severely limited—regardless of whether a nation was directly targeted. Critical industries would fracture. The impact to our supply chain would be far worse than what we saw during COVID-19. States would likely stop trading altogether. In fact, it would be near impossible to communicate with one another when the internet stops working, another probable effect of nuclear winter. Recognizing the devastation nuclear weapons cause, the Assembly calls on states to investigate and understand the environmental, social, military, and economic impacts of nuclear conflict. This includes cooperative scientific efforts to study how even a limited exchange could disrupt economies, displace populations, destabilize regions, and devastate ecosystems.

Very little investment has gone into studying the impact of nuclear war. There has been a striking absence of sustained international research, planning, or coordination especially when nuclear winter would affect the entire international community. On the flip side, individual governments have largely failed to confront the full scope of what nuclear war would entail, avoiding accountability for the risks they assume on behalf of their populations. As such, the Assembly also urges states to support the work of the forthcoming UN Independent Scientific Panel on Nuclear War Effects, which will offer a crucial, evidence-based assessment of the global consequences of nuclear use. This will be the first panel of its kind convened by the UN since 1988, almost four decades ago. It represents a long-overdue effort to inject scientific clarity and moral responsibility into the global conversation around nuclear weapons.

The greatest threat we face today is not simply the power of the bomb, but the failure of political courage. We understand the danger, and we know what we must do.  What’s missing is the will to act. Governments are unlikely to take steps toward disarmament or risk reduction without public pressure, pressure that must come from the ground up. Just as mass movements have shaped policy before, a broad coalition of scientists, academics, civil society groups, and faith communities can help force nuclear threats back onto the global agenda. That is why the Assembly calls on them to mobilize—to challenge apathy, cut through political silence, and help build the momentum needed to push world leaders toward meaningful, lasting, and entirely possible reductions in nuclear risk.