Did Ukraine Undermine Russia's Strategic Deterrent?

What are the nuclear implications of Operation Spiderweb?

Picture: UK Ministry of Defence

On June 1, 2025, Ukraine’s Security Service (SBU) executed Operation Spiderweb—a covert drone assault on the Russian Air Force’s Long-Range Aviation assets. The strike targeted five airbases: Belaya, Dyagilevo, Ivanovo Severny, Olenya, and Ukrainka.

According to current reports, Ukraine deployed 117 FPV drones, smuggled into Russia and launched from concealed trucks. The targets included Tu-95, Tu-22, and Tu-160 strategic bombers, as well as transport and AWACS aircraft. Ukraine maintains that 41 aircraft were destroyed in the attack. Independent analysts at Jane’s have confirmed at least 22 aircraft as heavily damaged or destroyed.

Several of the targeted platforms, particularly the strategic bombers, may have contributed to Russia’s nuclear deterrent, prompting some analysts and commentators to characterize the attack as having crossed major thresholds and potentially constituting a dangerous escalation. This post examines to what extent the strike has undermined Russia’s nuclear operations and whether it will have a lasting impact on its nuclear posture.

Russia’s strategic nuclear deterrent

Russia, at present, is estimated to deploy around 1,600-1,700 strategic nuclear warheads on about 700 strategic nuclear delivery vehicles. The latter include intercontinental ballistic missiles (ICBMs) launched from silos and mobile transporter erector launchers, submarine-launched ballistic missiles (SLBMs), and strategic bombers.

There has been some uncertainty regarding these numbers since 2023, when Russia unilaterally suspended its participation in the New START Treaty, which capped U.S. and Russian arsenals at 700 strategic nuclear delivery vehicles and 1,550 deployed strategic warheads.

Without treaty-based verification measures, precise insight into the size of Russia’s arsenal is no longer possible, at least not without access to classified intelligence. Nevertheless, there are no indications that Russia has meaningfully expanded its deployed strategic nuclear arsenal since 2023.

The majority of deployed strategic nuclear assets are ICBMs, located in stationary silos and on mobile transporter erector launchers. These account for roughly 60 percent of deployed strategic nuclear delivery systems and carry just over 50 percent of deployed strategic nuclear warheads. SLBMs deployed on nuclear-powered ballistic missile submarines (SSBNs) rank second, comprising close to 30 percent of delivery systems and carrying around 37 percent of deployed warheads.

The air-based leg of Russia’s strategic nuclear deterrent

In comparison to the land and sea-based legs, the air-based leg of Russia’s nuclear triad constitutes its smallest component. Under the New Start Treaty, Russia counted 60–70 Tu-95MS/MSM and Tu-160 strategic bombers as strategic nuclear delivery vehicles, representing only around 10 percent of deployed strategic nuclear delivery vehicles. We can assume that Russia has earmarked a similar number of strategic bombers for nuclear missions following its treaty suspension.

Ukraine maintains that it destroyed 41 long-range aviation assets in the attack. Independent analysis has confirmed 22 aircraft, most of which appear to be strategic bombers. Unfortunately, it remains unclear whether any of the destroyed strategic bombers were earmarked for nuclear missions. Russia maintains its strategic bomber fleet as fully dual-capable, without dividing it into distinct “nuclear” and “conventional” sub-fleets.

This stands in contrast to the United States, which has fully converted its B-1B bombers to conventional-only roles, rendering them incapable of nuclear missions. Additionally, only a portion of the U.S. B-52H fleet remains nuclear-capable, with those aircraft identifiable by the so-called “New START fins” located on the mid-aft fuselage.

For Russia’s long-range aviation forces, the distinction between nuclear and conventional roles exists only at the warhead level munitions — and only when those munitions are actually loaded onto the aircraft. The same crews launching Kh-101 or Kh-555 air-launched cruise missiles against Ukraine are also trained for nuclear missions, in which case they would employ nuclear-armed Kh-102 or Kh-55 cruise missiles.

This means that Ukraine effectively destroyed as many nuclear-capable bombers as it did conventional ones. In other words, by taking out at least 18 percent of Russia’s strategic bomber fleet (if we assume around 20 strategic bombers were lost), Ukraine also eliminated 18 percent of all bombers that could theoretically serve as nuclear delivery platforms. However, given the strict dual-role nature of these aircraft, the distinction is operationally irrelevant.

What is more important, in my view, is that Ukraine likely destroyed the most operational segment of the fleet, evidenced by the fact that these aircraft were not undergoing maintenance at the time of the attack. Some were even fueled when hit, indicating they were likely scheduled for use within the next 24 hours.

A major escalation?

Does the fact that Ukraine took out a number of strategic nuclear delivery vehicles mean it crossed major thresholds? While we can’t access the internal deliberations of Russian decisionmakers, I consider it unlikely that Russia viewed its secure second-strike capability as being threatened.

As noted above, the air-based leg of Russia’s nuclear triad accounts for only about 10 percent of strategic nuclear delivery vehicles, which are supposed to deliver around 11 percent of Russian strategic nuclear warheads in case of a major nuclear confrontation (at least in the initial attack run). In other words, Russia’s nuclear posture does not prioritize the airborne leg, a reality that is both well understood and intentional.

The air-based leg is widely regarded as the most vulnerable of the three legs in the triad. They are slow to launch (unless they are deployed on airborne or runway alert), can require hours to reach targets, and can be detected and intercepted by enemy air defenses. Moreover, unlike silo and TEL-based ICBMs or submerged SSBNs, bombers are “soft” targets concentrated around a relatively small deployment area, making them especially vulnerable to preemptive strikes.

In fact, it is unlikely that Russia views its strategic bomber force as survivable in a full-scale nuclear war. Instead, its second-strike capability is fully anchored in its more mobile assets, particularly its SSBN-based SLBMs and road-mobile ICBMs. As such, the operational significance of the destroyed bombers is likely greater in the conventional domain than in the nuclear one.

From an escalation management perspective, strikes on Russia’s air-based leg are therefore inherently less escalatory than attacks on more critical nuclear assets. For instance, if Ukraine were to destroy a docked SSBN undergoing maintenance, it could deal a major blow to Russia’s nuclear deterrent, given the important operational role each SSBN plays in nuclear deterrence missions.

While Ukraine is fully within its rights to target any military asset it deems necessary, Ukrainian decisionmakers must assume that strikes against these types of components of Russia’s strategic deterrent would be seen as crossing significant thresholds by Russia — and would almost certainly provoke major concern among Western governments.