There were no calamitous new developments last year with respect to nuclear weapons—but this is hardly good news.

Longstanding concerns about nuclear weapons—involving the modernization and expansion of arsenals in all nuclear weapons countries, the build-up of new capabilities, the risks of inadvertent or deliberate nuclear use, the loss of arms control agreements, and the possibility of nuclear proliferation to new countries—continued or were amplified in 2024. The outgoing Biden administration showed little willingness or capacity to pursue new efforts in these areas, and it remains to be seen whether the Trump administration will seize the initiative. At this time, it is difficult to anticipate when and how these negative trends may be slowed and, ultimately, reversed.

Against the backdrop of Russia’s continuing war against Ukraine, Russian President Vladimir Putin suspended compliance with the New Strategic Arms Reduction Treaty (New START), and Russia’s Duma voted to withdraw Moscow's ratification of the Comprehensive Nuclear Test Ban Treaty. Western officials confirmed in March 2024 that Russian nuclear weapons have been deployed in Belarus. In August 2024, Ukrainian forces entered Russia’s Kursk Oblast, and Ukraine subsequently attacked targets deeper into Russia, using US-supplied missiles with Washington’s permission. Russia revised its nuclear doctrine to signal a lower threshold for the use of nuclear weapons, and it used an intermediate-range ballistic missile against a Ukrainian target.

China’s nuclear arsenal has grown to about 600 warheads, and China may also now be deploying a small number of warheads on missiles during peacetime. In September 2024, China tested an intercontinental ballistic missile (DF-31AG) aimed at a location in the South Pacific 11,700 kilometers away; this was the first time China used the Pacific for a missile test since 1980.

At the same time, China is trying to engage other nuclear weapon states in nuclear diplomacy. In July 2024, China submitted a short working paper to the Preparatory Committee for the 2026 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). The paper “encourages the five nuclear-weapon States to negotiate and conclude a treaty on ‘mutual no-first-use of nuclear weapons’ or issue a political statement in this regard.” In October 2024, Sun Xiaobo (director general of the Department of Arms Control of the Ministry of Foreign Affairs of China) said at the general debate of the UN General Assembly First Committee: “Nuclear-weapons States should negotiate and conclude a treaty on ‘mutual no-first-use of nuclear weapons’ or issue a political statement in this regard, in order to prevent nuclear arms race and reduce strategic risks.” These no-first-use overtures, however, received no response from the other four permanent members of the UN Security Council.

In the Middle East, Iran continues to increase its stockpile of enriched uranium. US Secretary of State Antony Blinken said in July 2024 that Iran is one or two weeks away from producing enough highly enriched uranium for a nuclear weapon. Meanwhile, International Atomic Energy Agency Director General Rafael Mariano Grossi has reported that the IAEA has lost continuity of knowledge with regard to important equipment and materials in Iran’s nuclear program. Grossi also said that he is seeking talks with Iran’s new president, Masoud Pezeshkian, who has offered to open new nuclear negotiations with the United States and its partners in return for lifting sanctions that are crippling his country’s economy. Since April 2024, Israel and Iran have engaged in direct missile and drone attacks, and there are concerns that nuclear facilities could be targeted, which could quickly escalate the current crisis.

North Korea is estimated to have assembled on the order of 50 nuclear weapons, but Kim Jong Un recently declared his goal was to “exponentially expand” North Korea's nuclear arsenal in coming years. North Korea deployed troops to Russia for use in the war in Ukraine and reports of assistance for Pyongyang’s nuclear and missile program emerged. In October 2023, North Korea’s experimental light water reactor apparently began operations. The reactor could provide North Korea with a robust source of tritium to sustain an arsenal on the order of 100–150 thermonuclear weapons. North Korea also revealed a second uranium enrichment plant in 2024.

The United States can no longer be counted on as a voice of caution or nuclear moderation. Long a driver in the effort to prevent nuclear weapons use, reduce nuclear risks, and pursue nuclear arsenal reductions, the United States has embarked on the world’s most expensive nuclear modernization, and the 2024 election results suggest the United States will pursue a faster, more expansive nuclear investment program. It is possible that the United States will expand its nuclear efforts to include more nuclear options, rely more on nuclear brinkmanship to advance its security and deterrence goals, and shun proven efforts to reduce nuclear dangers. The United States is now a full partner in a worldwide nuclear arms race.

Read the 2025 Doomsday Clock statement »