Non-proliferation, SIPRI’s warning: “The world heading for nuclear rearmament”

Brussels – The era of nuclear disarmament and non-proliferation may be coming to an end. According to the latest report by an authoritative Scandinavian think tank, the rhythm with which states are re-arming is exceeding that with which, in recent years, atomic warhead holders were dismantling their arsenals. This is the first time we have seen this trend, whose protagonists are mainly the US and Russia, since the end of the Cold War.

In its annual report on the state of global security and armaments released today (16 June), the Stockholm International Peace Research Institute (SIPRI) puts it in writing that “a new and dangerous nuclear arms race is emerging at a time when arms control regimes are severely weakened“.

According to SIPRI’s calculations, at the beginning of 2025, the world’s nuclear arsenal amounted to 12,241 units, concentrated in the hands of nine states: the United States, Russia, the United Kingdom, France, China, India, Pakistan, North Korea, and Israel. This figure puts together the warheads ready for potential use—a total of 9,614 devices, of which 3,912 are already armed on missiles and aircraft (about 2,100 of these would be in a state of ‘high operational alert’) and 5,702 stored in warehouses—and those retired (i.e. retired but not dismantled), which stand at 2,627. Almost all of these warheads belong to Washington and Moscow.

During the past three decades, thanks to the efforts made under the global non-proliferation regime, the planetary stockpile of nuclear weapons had progressively diminished. But that trend has stopped and, indeed, is now in danger of being reversed due to the slowdown in disarmament and the parallel acceleration of arsenal modernisation programmes.

“The era of reducing the number of nuclear weapons in the world, which has lasted since the end of the Cold War, is coming to an end,” observes analyst Hans Kristensen. Moreover, he continues, today we are also witnessing ‘the escalation of nuclear rhetoric (think of the Kremlin’s threats to use nukes in Ukraine and the recent escalation between Israel and Iran, ed) and the abandonment of arms control agreements‘.

For SIPRI director Dan Smith, “the bilateral nuclear arms control between Russia and the United States entered a crisis several years ago” and is now nearing its end. The New START, the last non-proliferation agreement concluded by Washington and Moscow in 2010, will formally remain in force until February 2026. But neither side appears willing to renew it or replace it with other binding instruments. US President Donald Trump does not intend to tie the Pentagon’s hands unless China also agrees to reduce its arsenal, a rather unrealistic prospect.

On the contrary, according to Smith, “a new arms race
is gearing up that carries much more risk and uncertainty than the last one,”

i.e. the one between World War II and the collapse of the Soviet Union. Changing the game, of course, is the level of technological development, driven by advances in artificial intelligence, circuit capabilities, missile systems, space capabilities and quantum technologies.

Of course, the number of states interested in developing their own nuclear programme or sharing the stockpiles of allied countries is growing. This is the case, for example, of the Russian warheads deployed in Belarus (along the lines of the US nukes hosted by NATO members, such as Italy), or the hypotheses of extending the Franco-British nuclear umbrella to the rest of the Old Continent.

In numerical terms, the USA and Russia currently hold around 90 per cent of the world’s atomic weapons. For now, there is little change in the size of their respective arsenals. Still, SIPRI points out that both countries are implementing extensive modernisation programs for their stockpiles, which will likely lead to an increase in both the overall number of warheads and their variety.

The fastest-growing arsenal is that of Beijing, with an estimated 100 new warheads added per year starting in 2023. To date, the Stockholm Institute certifies, the People’s Republic has at least 600 nuclear warheads and could have about a third of those of the US and Russia by 2035. The stockpile of the United Kingdom is also expected to grow, as are those of India and potentially even Pakistan, with all the risks that come with the never-ending tensions between the two neighbours.

It is also estimated that North Korea has an estimated 50 warheads, that it has enough fissile material to produce 40 more, and that it is accelerating its uranium enrichment programmes. Finally, although it has never publicly admitted to possessing nuclear weapons, it appears that the Jewish state is also expanding and modernising its arsenal, although no reliable numbers are available on this.

The director of the International Atomic Energy Agency (IAEA), Rafael Grossi, did not directly confirm that Tehran is developing the bomb—as Tel Aviv claims, reiterating an accusation it has been making against the Islamic Republic for decades without ever having provided proof—but he did admit that he could not guarantee that the Ayatollah’s uranium enrichment programme is for civilian use only, as required by international agreements.