A nuclear state’s greatest responsibility is to keep its warheads secure. Since Russia invaded Ukraine in February 2022, it has put approximately 30 percent of its estimated 5,580 warheads in an untenably precarious position. Early in the war, concerns that the invasion increased the danger of a nuclear detonation or accidental explosion focused on the risk to Ukraine’s four nuclear power plants and Russia’s threats to intentionally escalate the conflict past the nuclear threshold. But the more Ukraine seeks to hit targets inside Russia, the clearer it becomes that Russia’s unwillingness to adequately secure the nuclear arsenals it has stored in its west—which are now within striking distance of Ukrainian missiles and drones and even Ukrainian troops—poses a dire risk.

Every week, Russia is launching up to 800 guided aerial bombs and over 500 attack drones at Ukrainian cities and energy plants. In response, Ukraine has begun launching up to hundreds of drones daily at carefully selected Russian targets.Ukraine has every right to defend itself in this manner, and there is no indication that Ukrainian forces would intentionally target nuclear warhead storage sites. Because Ukrainian drone assaults have already reached as far as Moscow, however, it is clear that at least 14 Russian nuclear storage sites now fall within range of its drones. At least two of those sites are less than 100 miles from the Ukraine border, well within striking range of the more damaging missiles Ukraine already possesses, and another five sites lie less than 200 miles from the border, close to or just beyond the range of the advanced Western-provided missiles that Ukraine is seeking permission to use against conventional targets in Russia.

The responsibility to move its nuclear warheads out of the way of danger lies with the Russian government. Russia knows that its warheads should not be positioned anywhere near conventional military operations: after Ukraine launched its first drone and missile attacks against Belgorod in the spring of 2023, Russia quickly reported that its Belgorod storage site was no longer storing nuclear warheads—acknowledging that warheads should not be stored anywhere near active fighting. But remarkably, there have been no Russian announcements about the status of the warheads it has at any of its other storage sites. There are several possible reasons for Russia’s clear dereliction of duty here: Russian President Vladimir Putin may believe that moving Russian nuclear warheads would be a sign of weakness; senior Russian leaders may not recognize the dangers posed to these warheads; or the Russian military may fear that the West would misconstrue moving warheads as preparations for a nuclear attack, prompting a pre-emptive strike by NATO.

The country that likely has the most influence over Russia’s handling of its nuclear arsenal is China. In September, Beijing became coordinator of the Nuclear Nonproliferation Treaty’s P5 process, a forum of the five original nuclear weapons states—China, France, Russia, the United Kingdom, and the United States—designed so those countries could jointly discuss their responsibilities. In this capacity, the Chinese leadership can—and must—lead a collective effort to persuade Russia to secure its vulnerable warheads, drawing on its own expanding bilateral relationship with Moscow. If China does not push for this, the risk that Russian nuclear sites become entangled in its war on Ukraine will only continue to grow, with potentially catastrophic consequences both for Russia and for the rest of the world. The possibility that a Ukrainian drone or missile will strike a warhead and create an explosion that distributes fissile material is already a major risk. But it is not the only one. Even more dangerous is the possibility that a Ukrainian missile strike or territorial takeover could throw a storage site into operational chaos, allowing rogue actors to seize its nuclear warheads—or inadvertently prompt Russian nuclear escalation.

WARHEAD GAMES

In 1991, as the collapse of the Soviet Union appeared imminent, the U.S. Congress established the Cooperative Threat Reduction (CTR) program, which aimed to help Russia secure the vast Soviet nuclear arsenal of approximately 30,000 nuclear warheads that it inherited. Because these storage sites were no longer overseen by the Soviet police state, their locations were no longer secret, they had little or no security equipment, and their guards were not getting paid. With the CTR’s assistance, Russia reduced its number of warheads and consolidated its arsenal within 42 existing storage facilities that were equipped with modern security features. The warheads were secured at three kinds of sites: 12 large central locations that housed hundreds of strategic and nonstrategic warheads; 30 smaller storage facilities adjacent to military bases, which stored dozens of warheads that could be fitted to the missiles, submarines, ships, or aircraft at the bases; and three rail transfer points where warheads can be transferred to and from trains to trucks. Russian warheads are frequently moved for maintenance and safety checks, so these transfer points almost always have warheads at them—and these rail transfer points are where the warheads are most vulnerable, because they are not in secure bunkers and are protected only by the trucks’ and rail cars’ reinforced exteriors.

In the immediate aftermath of the Cold War, most experts viewed the primary threat to Russia’s nuclear stockpiles to be a potential terrorist attack—which could even be carried out by up to 12 assailants—rather than armed conflict with another well-armed state. Over the course of 30 years leading the CTR’s bilateral effort to secure Russia’s warheads, I met more than 75 times with the leaders of the organization within Russia’s Defense Ministry responsible for maintaining and securing Russia’s nuclear arsenal. I visited dozens of Russian nuclear warhead storage sites, including those in Belgorod and Voronezh, near Russia’s border with Ukraine. And by 2008, Russia’s nuclear arsenal appeared relatively safe from such a terrorist threat. Security upgrades had been installed at all the warhead storage sites and rail transfer points. Every storage site was provided with three layers of security fencing, microwave and fence disturbance sensors, lights, video cameras, new security gates, and a fully equipped security control building.

But these upgrades were not designed to protect the warheads from attacks by a well-armed military force—and they cannot do so. When Russia initiated its full-scale invasion of Ukraine, it brought a conventional war near areas where hundreds of nuclear warheads are stored. Russia’s Belgorod central storage site, which may have stored hundreds of nuclear warheads, is located less than 30 miles from the Ukrainian border north of the city of Kharkiv, where Russia instigated heavy fighting. It is also just south of the Kursk region, where Ukrainian forces launched a major incursion into Russia in August and where fighting continues now. Russia reported that it removed all the warheads from this site, but it is not clear if that was done before or after the fighting began. Moving nuclear warheads during a conventional war is extremely dangerous behavior and would demonstrate that Russia is no longer a conscientious nuclear power. The warheads could have been struck accidentally by drones or missiles—or deliberately attacked or stolen.

The major Voronezh storage site, although it is farther east, is still less than 190 miles from the Ukrainian border. Already, there have been multiple drone attacks less than 100 miles from it.

Russia has also breached a sacred tenet of nuclear security by launching attacks against Ukraine from military bases that store nuclear warheads, thus making those bases a legitimate target for counteroffensives. Since March 2022, for instance, Russia has been using the Engels-2 air base 500 miles southeast of Moscow to launch Kinzhal missile attacks on Ukraine. Kinzhal missiles are dual capable, meaning they can carry nuclear warheads, and there are probably dozens of nuclear warheads stored less than four miles from the Engels-2 base’s main airfields. Ukraine has allegedly repeatedly attacked this air base with drones, including as recently as mid-September. Russia is believed to store dozens of nuclear warheads for short-range aircraft at the Yeysk air base, an installation directly across the Sea of Azov from Mariupol. Dozens more may be stored at Morozovsk, another aircraft base less than 100 miles from Luhansk, where Russian forces are fighting off Ukrainian troops to try to recapture lost territory. The longer the war continues, the more one or more of these sites risk getting caught in crossfire—an outcome that could have devastating consequences.

TIME BOMB

A strike on a storage site would not in itself cause warheads to detonate in a nuclear explosion. But if a warhead is not in its bunker because it is being moved for maintenance within the storage site or at a rail transfer point, and it is hit by an armed drone or missile, that could cause a major explosion that would release fissile material and render a several-mile radius uninhabitable for years. International observers might not even be able to judge how catastrophic such a strike had been, because Russian reporting on nuclear incidents historically cannot be trusted. And even if an attack did not directly strike a warhead, it could damage nuclear security systems or kill guards, thus rendering the warheads vulnerable to theft.

Nuclear warheads are especially unsafe when they are located at Russia’s rail transfer points. Although it is unclear whether Russia is currently moving warheads through any of these sites, if it is doing so, then a Ukrainian drone or debris from a bomber, Russian air defense system, or missile attack could easily hit them. Given that Russia has an inventory of thousands of warheads, there are almost always a handful that are being moved for maintenance. Ukraine, the United States, NATO, and open-source satellites may not be able to differentiate whether Russia is transporting warheads for maintenance or security—or to a military base from which they might be launched. Imagine if the United States or Ukraine detected a covert warhead movement and interpreted it to be part of an intentional operation against Ukraine or a NATO country: they would have to consider targeting that warhead shipment preemptively.

Beyond the immediate risks, storing nuclear warheads in a war zone increases the likelihood of escalatory actions by the Kremlin. Russia’s nuclear doctrine holds that an attack on any element of its deterrent force justifies a nuclear response. It is not clear whether an accidental strike on a nuclear warhead storage site would cross a Russian nuclear redline, but Putin has recently sought to draw attention to his country’s escalation doctrine. The fact that its nuclear warheads are so close to Ukraine could, in fact, tempt Russia to conduct a false-flag operation on its own storage sites in order to justify a nuclear attack.

But perhaps the greatest danger now posed by Russia’s nuclear weapons storage sites is the one that was originally envisioned after the Cold War’s end: that is, the danger that warheads could be seized by a small, rogue group of fighters. Russia still faces internal threats including terrorists, separatists, and the thousands of former Wagner fighters now scattered across Russia and Belarus. Its actions in Ukraine have greatly exacerbated the danger posed by these long-standing threats.

On August 6, Ukrainian troops entered Russian territory and captured a swath of the Kursk region—an area that lies between two large Russian storage sites (in Bryansk and Voronezh) housing hundreds of warheads. The concern is not that the Ukrainian military would do something hazardous with loose nukes. But if the Ukrainian military were to attack or drive Russian security forces away from a storage site, rogue actors could enter the site and seize its warheads. Former members of the Wagner paramilitary company, for instance, might wish to use such warheads against Ukraine, or Russians fighting on Ukraine’s behalf might wish to attack a Russian city. A single Russian actor could instigate such an operation with or without direction from Russian authorities. And with its military tied up in Ukraine, Russia simply may not have military forces available to respond to an attack on a warhead storage site or convoy.

RESTORING TRUST

To truly safeguard its nuclear arsenal, Russia would need to end its onslaught against Ukraine and the increasingly complicated cross-border conflict that its invasion has generated. But with no instant end to the war in sight, more immediate steps must urgently be taken. In the near term, Russian nuclear warheads must be removed from any base that is close to wartime operations and bases from which Russia is launching conventional attacks. Thus far, Russia has failed to move its warheads out of danger. Russia believes that its advantage in nonstrategic nuclear weapons serves to deter Ukrainian and Western escalation against Russia. But in truth, if Russia wants to maintain that advantage, it must end the war or relocate the warheads to safer locations. Nuclear deterrence does not depend on warheads being located on a country’s frontlines. In fact, a country best maintains its deterrence if it stores its nuclear weapons well out of harm’s way.

Russia must immediately facilitate the safe movements of all of its warheads located within 500 miles of the Ukraine border to storage sites east of the Ural Mountains. China, which has become a crucial partner for Russia since the war began, is in the best position to press Russia on this point. It can push Russian leaders to secure their warheads during bilateral discussions or within the P5 forum. Ultimately, China cannot view Russia as a credible nuclear power, or partner, if Russia cannot secure its nuclear warheads away from military operations.

The other countries that are signatories to the Nuclear Nonproliferation Treaty as well as the members of the UN General Assembly can also pressure Russia. If Russia does not agree to move its warheads after this concern is raised by the P5 and the UN, repercussions as severe as the country’s temporary or permanent removal from the UN Security Council are warranted. As a signatory to the NPT, China may even support such an action: Beijing cannot, in fact, afford any incident involving nuclear weapons to occur as a result of the war in Ukraine, because that would draw much more scrutiny to its own nuclear buildup. The world must convince Russia that it is fundamentally endangering its reputation as a responsible nuclear power: its management of its nuclear arsenal over the past two and a half years clearly violates the basic responsibilities expected of nuclear states.