The world’s nine nuclear-armed states are modernizing and upgrading their arsenals as crucial arms-control frameworks like the Strategic Arms Reduction Treaty between the U.S. and Russia, known as New START, have largely eroded or collapsed outright.
The Stockholm International Peace Research Institute said in a new report that countries are increasingly relying on nuclear weapons as instruments of national power.
The trend threatens to reverse decades of deals to reduce the numbers and roles of nuclear weapons, even as the risks of miscalculation and escalation are rising, SIPRI analysts said in the study.
“Influential voices, including some world leaders, are advocating nuclear weapons as a guarantee against attack by a nuclear state,” SIPRI Director Karim Haggag said. “But, making national defense and security strategies dependent — or more dependent — on nuclear weapons could significantly increase nuclear risks.”
There are an estimated 12,187 nuclear weapons worldwide that are possessed by the nine countries: the U.S., Russia, the U.K., France, China, India, Pakistan, North Korea and Israel. Just over 9,700 were in military stockpiles for potential use. The rest have been retired but remain intact until they are dismantled, analysts said.
The U.S. and Russia control more than 80% of all stockpiled nuclear warheads. The SIPRI analysts said the combined share is shrinking somewhat due to the growth in the world’s other nuclear arsenals.
“The sizes of the Russian and U.S. military stockpiles appear to have stayed relatively stable in 2025, but both sides’ extensive modernization programs seem likely to increase the size and diversity of their arsenals in the future,” the report said.
The U.S. maintains a stockpile of about 3,700 warheads, relatively unchanged from the previous year. Of that number, about 1,700 are deployed while approximately 1,930 are held in reserve. In addition, about 1,300 retired warheads are awaiting dismantlement, analysts said.
“The United States and Russia now possess approximately 86% of the world’s total inventory of nuclear weapons, and 83% of the stockpiled warheads available for use by the military,” according to a statement from the Federation of American Scientists. “No other nuclear-armed states see a need for more than a few hundred nuclear weapons for national security, although many of these states are increasing their nuclear stockpiles.”
A Russian nuclear weapon increase would mainly happen as a result of modernizing the country’s remaining strategic forces to carry additional weapons on each missile. The U.S. increase could result from more warheads being deployed to existing launchers, empty launchers being reactivated, and new non-strategic nuclear weapons being added to the nation’s arsenal, the SIPRI analysts wrote.
Washington’s comprehensive nuclear modernization program is progressing. However, it is facing continued planning and funding challenges from last year that will likely cause further delays and increase the program’s cost, analysts said.
Russia’s program is also facing challenges. Western economic sanctions and competing demands linked to Moscow’s war against Ukraine seem to have played a part in last year’s launch failure of the Sarmat intercontinental ballistic missiles.
China has around 620 nuclear warheads and is expanding its atomic arsenal faster than any other country. Beijing showcased several new nuclear systems during its 2025 military parade. By January 2026, China had loaded hundreds of missiles into three large silo fields in the north of the country, while working to complete 30 additional ICBM silors in three mountainous areas in the east.
“China could potentially have at least as many ICBMs as either Russia or China by the turn of the decade,” the report said. “Yet even if China surpasses 1,000 warheads by 2030, that will still amount to only about one quarter of each of the current Russian and U.S. nuclear stockpiles.”
The U.K. is expected to grow its operational warhead stockpile in the future, although London no longer publicizes the size of its nuclear arsenal. Last year, the U.K. announced its intention to buy 12 nuclear-capable F-35A combat aircraft from the U.S. and equip them with U.S. nuclear bombs. The plan walks back a 1990s-era decision to denuclearize the Royal Air Force.
North Korea has likely assembled around 60 nuclear warheads and possesses sufficient material to produce at least 30 more. Last year, Pyongyang continued to unveil and test new missile systems, including the solid-fueled Hwasong-20 ICBM, along with medium-range systems designed to evade missile defenses, according to the report.
Finland, one of the newest NATO members, is moving toward lifting its decades-old total ban on nuclear weapons. The change doesn’t mean Helsinki wants its own atomic arsenal, however. It will remove legal barriers so NATO countries can legally transport or temporarily deploy nuclear deterrents through Finnish territory or airspace during a time of crisis.
The repeal puts Finland on a legal footing with Nordic neighbors like Norway and Sweden.
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