Robert Oppenheimer, America’s father of the atomic bomb, described his country’s nuclear rivalry with the Soviet Union as “two scorpions in a bottle.” The risks of this standoff have been managed by various arms-control agreements over the years, most recently New START. But that treaty expires on February 5, without any replacement — and to make matters more dangerous, there’s a third scorpion in the bottle these days: China. Its nuclear buildup, the world’s fastest since the height of the Cold War, is likely to prompt a response from the US. A new arms race is starting.
When China’s leader Xi Jinping came to power in 2012, his country had only 240 warheads, a fraction of the 1,550 both the US and Russia were allowed to put on long-range launch vehicles under New START. American military planners recognized that in a nuclear war with China, America’s much larger arsenal would allow it to win in almost any scenario. But according to the latest US estimate, China now has about 600 weapons and is on track to reach 1,000 or more by 2030.
China still likes to boast of its “utmost restraint” in nuclear matters. After all, if you include weapons held in storage rather than ready for use, the US and Russia both have more than 5,000. A recent policy paper stated that China “does not and will never engage in a nuclear arms race with any other country”. But still the country has developed the capability to attack America with nuclear weapons from air, land and sea. a finely choreographed army parade These weapons were demonstrated last year, including a missile that was so huge it had to be carried in three sections.
The US has been unable to increase its nuclear arsenal in response while New START has been in place. Perhaps for this reason, it expresses little regret at the treaty’s imminent expiration. Russia says the expiration of the nuclear weapons ban should “alert everyone” and recently suggested both sides voluntarily abide by New START’s limits for another year. Some arms-control advocates hope that US President Donald Trump may pursue the idea even after the treaty expires. But he seems indifferent: “If it’s over, it’s over,” he said last month.
American planners are worried about war with both China and Russia. The US and its allies should “prepare for the possibility that…potential adversaries may act together in a coordinated or opportunistic manner in multiple theaters,” the recent national-defense strategy announced. This is “an existential challenge for which the United States is unprepared”, a bipartisan commission created by Congress concluded in 2023. China and Russia are increasingly pursuing shared objectives, exchanging sensitive technology and conducting joint military exercises, sometimes with nuclear bombers. America’s current nuclear force was not designed with China in mind, as it was considered a smaller threat than Russia. The expansion of China’s nuclear capabilities undermines that perception.
Philip Saunders of the National Defense University, a US military college, says China’s nuclear forces are undergoing several changes: They are not only getting bigger, but also more diverse, with a variety of warheads and launchers. They are being kept on high alert. And they are becoming more capable of what the Pentagon calls “launch on warning” (that is, detecting an attack and retaliating before enemy weapons arrive).
The latest Pentagon assessment says new satellites to detect missile launches and phased-array radars capable of tracking them could alert Chinese commanders to an attack within 3-4 minutes. China’s armed forces are also better capable of launching quick counter-attacks. Missiles respond fastest in silos filled with solid fuel (rather than volatile liquids that cannot be stored in the missile). The Pentagon says China has deployed about 100 silos in three vast areas, designed to hold 320 missiles. The country’s rocket forces are also practicing. In 2024 they fired a nuclear-capable missile 11,000 km into the Pacific Ocean. Three months later, they fired several missiles in rapid succession toward western China.
Experts debate why Mr Xi has ordered construction so rapidly. Mr. Saunders thinks he is pursuing three overlapping goals. First, it wants a nuclear arsenal capable of surviving any American attack, thereby ensuring it the capability to retaliate. Although this typically involves mounting missiles on hard-to-find submarines and mobile launchers, the proliferation of silos offers China a cheap and quick way to increase its arsenal.
Second, China wants a more flexible arsenal, capable of less destructive use than all-out nuclear war. The Pentagon believes China is developing smaller weapons, with a yield of less than ten kilotons (as opposed to the 400 or more mounted on larger intercontinental missiles). They could be mounted on intermediate-range missiles like the DF-26, and used against major US bases in Guam if, say, the US used similar, smaller nuclear weapons in a last-ditch effort to defend Taiwan from Chinese invasion (the DF-26 is nicknamed the “Guam Killer”).
Or Mr Xi could see a large nuclear arsenal as a symbol of “great-power status”. China already has more nuclear weapons than any country except Russia and the US (see chart). Does he want equality with his 5,000 or more weapons? Mr Saunders thinks China could aim for a “sweet spot” in the middle, to show China is a great power but also a responsible one.
China claims it would not be the first country to use nuclear weapons, but that theory is vague, says Tong Zhao of the Carnegie Endowment for International Peace, a think-tank in Washington, DC. This could lead to the threat of using nuclear weapons, as Russia has done in Ukraine. Or it could fire a warning shot over the ocean, or explode at high altitude to destroy satellites. “If China is facing an ugly and devastating conventional defeat, no one can rule out that it might decide to use nuclear weapons first,” Mr Zhao says. “Ultimately authority rests with only one person.”
If China’s intentions are uncertain, America’s response is also uncertain. A recent paper by the Heritage Foundation, a think-tank, calls for more than doubling the total number of deployed weapons from 1,770 to 4,625 by 2050. Others believe that the US already has more than enough live nuclear weapons to cause catastrophic damage to both Russia and China, although it may have to abandon the idea of destroying enough of the enemy’s weapons to limit damage to the US and its allies.
Vipin Narang, an official in Joe Biden’s administration, suggests a more modest deployment of 500 additional nuclear warheads, primarily to target China’s new silos. “There’s no magic number. It all depends on how much risk you’re willing to take,” he says. Former Pentagon nuclear planner Franklin Miller believes that about 300 would be enough.
Whatever the number, the build-up will be slow. The US is already struggling to modernize all three legs of its nuclear triad, build new ones sentinel land based missilesColumbia-class nuclear submarines and B-21 stealth bombers, as well as upgrading command-and-control systems. Some projects are too late or over budget.
For now, the US can only “upload” additional weapons from the stockpile onto existing systems. Installing more air-launched cruise missiles in bombers requires only a few days, but installing more warheads on missiles in nuclear submarines requires months. It will probably take two years to convert the Minuteman III land-based missiles from one warhead back to three. In 2023 the Federation of American Scientists, which monitors nuclear forces worldwide, calculated that the US could deploy about 1,900 more weapons by these methods, compared with 1,000 for Russia. It will take decades to expand America’s total reserves. If the nuclear arms race went that far, Uncle Sam would be at a disadvantage: It could make only a few new weapons a year while Russia could produce hundreds. However, Mr. Miller points out that the American plan is no longer based on Cold-War notions of exaggeration, but rather on “adequacy”: “If the Russians want to upload debris to bounce off, that’s their business.”
Whatever the pace of the new nuclear competition, the 40-year process of shrinking the nuclear stockpile is headed in reverse. An arms race more complex than the Cold War is looming. China is already expanding its arsenal; If the US moves in response, Russia is sure to follow. India may feel obliged to balance China and Pakistan may feel obliged to balance India. Another source of instability is the fear that Mr. Trump could abandon allies, which is leading some of them to think developing one’s own nuclear weapons. Recent US strategy documents on national security and defense say nothing about long-term commitments to protecting 30-odd allies and partners from nuclear attack. South Korea is especially worried. A Pentagon official who recently visited Seoul omitted to mention the threat from the nuclear-armed North. A world of relatively limited and known nuclear threats may soon become one of growing and unpredictable threats.
