What Is the Third Nuclear Age?

The world can be divided into three eras of nuclear weapons history, each defined by distinct weapons dynamics and geopolitical relationships, and distinguished by major proliferation or treaty events of its time.

The first nuclear era was characterized by a bipolar rivalry between the United States and the Soviet Union during the Cold War, from 1945 to the late 1980s. At its peak, the number of warheads held by both countries is estimated to have reached around 60,000 in 1986. This era was marked by limited arms control agreements and significant arms racing.

The second nuclear era, spanning from 1991 to 2013, saw significant disarmament through bilateral U.S.–Russia treaties such as START I and New START, which reduced global warhead numbers by a considerable amount. However, this period was also marked by nuclear proliferation efforts by regional actors, including the nuclearization of South Asia, particularly India, followed by Pakistan, and then North Korea’s decision to pursue nuclear weapons.

Beginning in 2014, the third nuclear era emerged, typified by the current, chaotic, multipolar environment. Russia has unilaterally suspended participation in New START monitoring and verification, a treaty that expired on February 5^th, 2026. Both the United Kingdom and France have commenced modernization and expansion of their nuclear forces. China is rapidly nearing an estimated 600 warheads, North Korea continues to test intercontinental ballistic missiles (ICBMs), and Russia has modernized its weapons systems and deployed short-range nuclear weapons in Belarus. Iran continues to signal that it is nearing the nuclear threshold, opacity persists regarding Israel’s nuclear capabilities, and the May 2025 conflict between India and Pakistan has created multiple additional flashpoints, all of which underscore the need for new international multilateral guardrails.

Current Global Nuclear Trends

The United States has initiated a $1.7 trillion nuclear triad modernization plan, which includes submarines, bombers, and land-based missiles. Russia has been testing nuclear-powered cruise missiles such as Burevestnik, while China is expanding its nuclear weapons capability at a rapid pace amid rising tensions over Taiwan.

In addition, strategic non-nuclear weapons, including hypersonic systems, AI-driven command structures, and missile defense, are contributing to an escalatory environment in which the nuclear ladder has become increasingly slippery to climb and equally difficult to descend. The Bulletin of the Atomic Scientists has set its “Doomsday Clock” at 89 seconds to midnight, the closest it has ever been since 1947, reflecting its assessment that the erosion of arms control, the expansion of nuclear capabilities, and the persistence of conflict have significantly increased the risk of nuclear catastrophe.

Escalating Global Nuclear Challenges

The U.S.-Russia arms control negotiations have ceased over Ukraine, and President Putin has reduced stated nuclear use thresholds. At the same time, U.S. military strikes against Iran have alarmed some observers who argue that such actions undermine norms governing sovereignty. NATO countries are increasingly exploring their own European deterrence capabilities.

A defining feature of the third nuclear age is the growing complexity of the strategic environment and the inability to manage global risks through simple bilateral frameworks.

Technological advancements that accelerate escalation risks include hypersonic weapons that challenge missile defense systems, artificial intelligence that may misinterpret launch indicators, and cyber operations that could inadvertently contribute to nuclear escalation—echoing historical false-alarm incidents in 1983. Meanwhile, China’s evolving relationship with Russia further complicates U.S. efforts to deter aggression across both Europe and the Asia-Pacific.

The Way Forward

With New START having expired, significant future limits on the number of nuclear weapons possessed by major powers appear unlikely, accelerating competition and instability. By the mid-2030s, the convergence of nuclear and advanced conventional capabilities may become normalized as tools of coercion rather than deterrence, while additional states may seek nuclear weapons should nonproliferation barriers erode. The Bulletin of the Atomic Scientists has identified the emergence of the “third nuclear age” as the top global risk in 2026.

Accordingly, new mechanisms for arms control and nuclear disarmament consistent with commitments made by major nuclear-weapon states under the NPT framework are urgently required. These include enhanced verification technologies, AI-assisted monitoring, restraints on the development of destabilizing new weapons, and sustained strategic-stability dialogue aimed at separating and disentangling nuclear and conventional escalation pathways. Additional measures to promote norms of responsible nuclear behavior are also necessary, although opposition from the five permanent members of the UN Security Council remains a significant barrier to progress. Ensuring the global security of radioactive materials must remain a priority.

The third nuclear age has placed humanity in unprecedented danger. Existing disarmament mechanisms have proven ineffective as new rivalries emerge, and technological changes accelerate. History demonstrates that diplomacy can work: New START reduced nuclear arsenals to their lowest levels since the early years of the first nuclear era. Today’s leaders must again prioritize cooperation and restraint, or risk allowing miscalculation to turn expanding arsenals into catastrophe. The alternative is too terrible to ignore.

Ms. Harsa Kakar is an Assistant Research Fellow at the Balochistan Think Tank Network (BTTN), Quetta. Views expressed in this article are the author’s own. 

Understanding the Third Nuclear Age: Why 2026 Matters was originally published on Global Security Review.

Most the world’s approximately 12,100 nuclear weapons are held by just a handful of major world powers. The U.S. and Russia hold nearly 87 percent of the world’s nuclear weapons, with Russia possessing approximately 5,500 and the US holding approximately 5,177, declared  weapons, many of which remain in a state of high alert. China possesses an estimated 600 operational nuclear weapons, with the number having grown by over 100 in recent years. France is estimated to have 290 warheads; the UK, 225; India, 180; and Pakistan, 170. These countries have all maintained stable stockpiles through modernization efforts. However, North Korea maintains an estimated 50 nuclear weapons, but is aggressively developing its nuclear delivery capabilities, including the development of solid-fueled ICBMs and nuclear-capable submarines with Russian backing.

These developments present the growth in nuclear arsenals and nuclear technology, rather than a reduction. The growth includes the qualitative development of nuclear delivery technology, such as hypersonic vehicles and Multiple Independently Targetable Reentry Vehicles (MIRVs), which has undermined the existing balance in the arms race established because of the Cold War.

The New Strategic Arms Reduction Treaty (New Start), which remains the last bilateral US-Russian nuclear weapons agreement, is scheduled to expire on February 5, 2026, without any proposed replacements because of disagreement on the treaty’s terms. In 2023, Russia withdrew from the inspection and data sharing provisions in relation to Ukraine, but the two countries have openly stated to voluntarily meet their respective limit requirements under the treaty since then. If the treaty is allowed to lapse, it is anticipated that each side could begin to increase their nuclear weapons arsenal, which could prompt other nuclear-capable states, including China, to do likewise.

Additionally, the upcoming review conference of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) set to occur in New York in April 2026, presents additional challenges. Past NPT review conferences have been unable to reach a consensus primarily because of the anger expressed by non-nuclear states toward nuclear-armed states for failing to meet their obligations under Article VI of the treaty to pursue disarmament. As a result of this failure, several treaties relating to the regulation of nuclear weapons, including the Comprehensive Test Ban Treaty (CTBT) have been signed but not ratified by key signatory states and therefore lack the needed verification mechanisms.

Iran may also be motivated to obtain nuclear weapons for the purpose of providing a deterrent against Israel’s expanding conventional and nuclear capabilities. Iran’s nuclear weapons program is one of the most pressing issues confronting the United States and Israel today. Iran is now stockpiling uranium-enriched to 60% levels that are close to the level of enrichment required to produce nuclear weapons. It is also developing new centrifuges at its underground facility, known as Fordow, and is shortening the time it takes to produce a nuclear weapon despite continuing economic sanctions and airstrikes against its military assets.

Further, North Korea indicated that 2025 would be a “crucial year” for its nuclear weapons development program and announced that it successfully tested its Hwasong-20 Intercontinental Ballistic Missile (ICBM) and has increased the size of its nuclear facility at Yongbyon; it intends to complete construction of missile factories by 2026. Regional conflicts on the Korean Peninsula and in the Middle East, especially those involving Iran and Israel continue to pose a substantial risk of unintended escalation in the increasingly complex and multi-polar world we live in today.

Disarmament is nothing more than a relic of a bygone era. Nuclear-armed states are engaging in modernization efforts and the language used by these states appears to lower the threshold for using these weapons, seen from Russia’s nuclear threats regarding Ukraine to the lowering of nuclear alert status. Verification is touted by some as much as possible through the International Atomic Energy Agency (IAEA); however, the nuclear powers are unwilling to provide the level of transparency needed to verify compliance with any proposed disarmament treaty. Furthermore, although non-proliferation efforts have successfully limited the number of new nuclear weapons being developed, until nuclear-armed states reduce their own arsenals, non-proliferation efforts will remain a hollow pillar.

In 2026, nuclear arsenals among the great powers are expected to continue expanding. At the same time, the expiration of New START is likely to lead to the failure of the NPT Review Conference, further weakening the Nuclear Non-Proliferation Treaty regime. These challenges will be compounded by the emergence of modern technologies, including artificial-intelligence–enabled command systems and hypersonic delivery vehicles, which increasingly blur the line between conventional and nuclear capabilities. When combined with the proliferation activities of states such as Iran and North Korea, these developments will place unprecedented strain on diplomatic efforts to prevent conflict and miscalculation. This risk is heightened further by escalating tensions among the world’s major powers.

Ms. Harsa Kakar is working as an Assistant Research Fellow at Balochistan Think Tank Network (BTTN), at BUITEMS, Quetta, Pakistan. She is an MS International Relations Scholar at BUITEMS, Quetta, and a distinguished graduate of International Relations from the University of Balochistan. She specializes in AI, Global Politics, Diplomacy, Soft Power, and Conflict Resolution. Views expressed in this article are her own.

The Dawn of 2026 and Challenges to Non-Proliferation was originally published on Global Security Review.

A driving factor is the rising nuclear threat posed by China, North Korea, and Russia. Such a threat requires effective nuclear deterrence. Another concern is continuing doubts as to whether America’s extended deterrence is reliable in a serious international crisis or a major shooting war.

It is true that when authoritarian states brandish their nuclear arsenals for coercion, repeatedly threatening nuclear attack, any nation would be concerned and look to its guarantor of security for help. Unfortunately, the United States is proving slow to field the kind of arsenal that can not only deter or defeat aggression against itself, but also provide that same capability for almost three dozen allies.

The US is now in a position where it must modernize and expand its own nuclear arsenal and right-size those numbers to sustain dynamic parity with adversaries. Legally and morally, there is indeed an inescapable duty to deter. For Japan and South Korea, that duty will be met by the United States or themselves.

Nuclear participation by America’s allies in Asia would be in direct contravention to US policy, and would violate both the letter and the spirit of the 1970 Non-Proliferation Treaty (NPT), but it would certainly prove understandable. Australia, Japan, and South Korea all signed the treaty, but a voracious and aggressive China and North Korea are proving a real threat to all three states.

Rather than take a position for or against ally nuclear participation, an overview of the main arguments on both sides of the issue are instructive.

Pros

First, recall that Australia, Japan, and South Korea all have a level of experience with the nuclear issue. Japan, of course, faced atomic bombings of Hiroshima and Nagasaki. But, as Japan up-arms to deter China and North Korea, Tokyo might decide to field its own nuclear weapons.

Southern and western Australia were the sites of over a dozen British nuclear weapon tests between 1952 and 1963. This is a fact too few understand.

South Korea had its own nuclear weapon research and development program during the Cold War, which was abandoned because of American pressure. South Korea does rely on nuclear power for its generation of electricity.

Second, note that these American allies do possess civilian nuclear power industries, sophisticated militaries, sizable economies, and advanced science and technology capabilities. All three countries could build nuclear weapons in relatively short order. On the positive side, the fielding of Australian, Japanese, and South Korean nuclear forces would make aggression far more complicated for China and North Korea.

The inclusion of allied nuclear forces would disperse and diversify the collective nuclear deterrent available for employment and increase the number of targets China or North Korea must strike in a conflict. Allied nuclear participation is also an alternative to overseas nuclear basing agreements, like those that existed during the Cold War. Given the lack of available American weapons, such an arrangement could prove very beneficial.

Lastly, nuclear participation would put an end to the endless debate over the credibility of  American extended deterrence. Rather, the focus would turn to integrating nuclear forces in the event of a conflict.

Cons

There are some well-known arguments for continued nuclear nonproliferation. They include the longtime prohibition in US policy and the NPT prohibition against it. There are also pragmatic concerns.

First, if a country were to withdraw from the NPT, although allowed by Article X, it would create significant diplomatic tensions between the US and the country withdrawing from the treaty. American sanctions could significantly harm the economy of Australia, Japan, or South Korea.

Second, any democratic state pursuing nuclear weapons would undermine Western efforts to halt Iran’s nuclear weapons development. Worse, it could open the floodgates of nuclear proliferation among states that are certain to prove less responsible with those weapons.

Third, China might see the pursuit of nuclear weapons by American allies as a sufficient reason to launch a “defensive” nuclear strike. China’s “active defense” strategy clearly supports the use of preventive attacks.

Fourth, the Nuclear Supplier’s Group would end all support to the civilian nuclear programs of Australia, Japan, and/or South Korea. Such a decision would cause great difficulty for power generators.

Conclusion

For Australia, American promises and the continent’s geographic position may prove sufficient to prevent a move to a nuclear weapons program. For Japan and South Korea, the threat is much closer. How these countries evaluate the threat is yet to be determined. They are signaling the United States that they want stronger assurances of American commitment.

Such assurance will prove difficult for the United States for many reasons. Neither China nor North Korea should take for granted that America’s allies will remain under the nuclear umbrella. It is only because of flagrant aggression that South Korea, and most recently, Japan, are even talking about the need for indigenous nuclear forces.

Joe Buff is a Senior Fellow at the National Institute for Deterrence Studies. Views expressed are his own.

The Pros and Cons of Nuclear Participation in the Pacific was originally published on Global Security Review.