What is a tactical nuclear weapon? An international security expert explains and assesses what they mean for the war in Ukraine | Catch My Job

Tactical nuclear weapons burst onto the international scene as Russian President Vladimir Putin, faced with battlefield losses in eastern Ukraine, threatened that Russia would “use all weapons systems available to us” if Russia’s territorial integrity was threatened. Putin has characterized the war in Ukraine as an existential battle against the West, which he said wants to weaken, divide and destroy Russia.

US President Joe Biden criticized Putin’s open nuclear threats to Europe. Meanwhile, NATO Secretary General Jens Stoltenberg downplayed the threat, saying that Putin “knows very well that a nuclear war should never be fought and cannot be won.” This is not the first time that Putin has invoked nuclear weapons in an attempt to deter NATO.

I am an international security expert who has worked and researched the theory of nuclear deterrence, non-proliferation and costly signaling applied to international relations for two decades. Russia’s large arsenal of tactical nuclear weapons, which are not regulated by international treaties, and Putin’s doctrine of the threat of their use have raised tensions, but tactical nuclear weapons are not just another type of weapon on the battlefield.

Tactical by numbers

Tactical nuclear weapons, sometimes called battlefield or non-strategic nuclear weapons, are designed to be used on the battlefield – for example, to counter superior conventional forces such as large formations of infantry and armor. They are smaller than strategic nuclear weapons like the warheads carried on ICBMs.

While experts disagree on the precise definitions of tactical nuclear weapons, lower explosive power, measured in kilotons, and shorter-range delivery vehicles are common features. Tactical nuclear weapons vary in yield from fractions of 1 kiloton to about 50 kilotons, compared to strategic nuclear weapons, which have yields ranging from about 100 kilotons to over a megaton, although much more powerful warheads were developed during the Cold War.

For reference, the atomic bomb dropped on Hiroshima was 15 kilotons, so some tactical nuclear weapons are capable of causing widespread destruction. The largest conventional bomb, the Mother of All Bombs or MOAB, dropped by the US has a yield of 0.011 kilotons.

Tactical nuclear weapon delivery systems also have a shorter range, typically under 500 kilometers compared to strategic nuclear weapons, which are typically designed to cross continents.

Because the explosive power of low-yield nuclear weapons is not much greater than that of increasingly powerful conventional weapons, the US military has reduced its reliance on them. Most of the remaining stockpiles, about 150 B61 gravity bombs, are deployed in Europe. Great Britain and France have completely eliminated their tactical stocks. Pakistan, China, India, Israel and North Korea have several types of tactical nuclear weapons.

Russia has retained more tactical nuclear weapons, estimated to be around 2,000, and has relied more heavily on them in its nuclear strategy than the US, largely because of Russia’s less advanced conventional weapons and capabilities.

Russian tactical nuclear weapons can be deployed by ships, aircraft and ground forces. Most are deployed on air-to-surface missiles, short-range ballistic missiles, gravity bombs and depth charges delivered by medium-range and tactical bombers, or naval anti-ship and anti-submarine torpedoes. These missiles are mostly kept in reserve in central warehouses in Russia.

Russia has updated its delivery systems to be able to carry nuclear or conventional bombs. There is increased concern about these dual-capability delivery systems because Russia has used many of these short-range missile systems, especially the Iskander-M, to bomb Ukraine.

Tactical nuclear weapons are significantly more destructive than their conventional counterparts even with the same explosive energy. Nuclear explosions are more powerful by factors of 10 to 100 million than chemical explosions and leave deadly fallout of radiation that would contaminate air, soil, water and food supplies, similar to the catastrophic failure of the Chernobyl nuclear reactor in 1986. Alex Wellerstein’s interactive NUKEMAP simulation site describes the multiple effects of nuclear explosions of varying yields.

Can any nuclear bomb be tactical?

Unlike strategic nuclear weapons, tactical weapons are not focused on mutually assured destruction through massive retaliation or nuclear umbrella deterrence to protect allies. While tactical nuclear weapons are not included in arms control treaties, intermediate-range weapons are included in the now-defunct Intermediate-Range Nuclear Forces Treaty (1987-2018), which reduced nuclear weapons in Europe.

Both the US and Russia have reduced their total nuclear arsenals from around 19,000 and 35,000 respectively at the end of the Cold War to around 3,700 and 4,480 in January 2022. Russia’s reluctance to negotiate on its non-strategic nuclear arsenal has hampered further nuclear arms control efforts.

The fundamental question is whether tactical nuclear weapons are more “usable” and therefore could potentially trigger full-scale nuclear war. Their development was part of an effort to overcome concerns that, since large-scale nuclear attacks were widely seen as unthinkable, strategic nuclear weapons were losing their value as a deterrent to war between superpowers. In theory, nuclear powers would be more likely to use tactical nuclear weapons, and thus the weapons would strengthen a nation’s nuclear deterrent.

However, any use of tactical nuclear weapons would challenge defensive nuclear strategies. In fact, then-Secretary of Defense James Mattis specifically stated in 2018, “I don’t think there is such a thing as tactical nuclear weapons. Any use of nuclear weapons at any time changes the strategy.”

The US has criticized Russia’s escalation-to-de-escalation nuclear strategy, in which tactical nuclear weapons could be used to deter the spread of war to NATO.

Although there is disagreement among experts, Russian and American nuclear strategies focus on deterrence, and therefore involve large-scale nuclear attacks over the use of a first nuclear weapon. This means that a Russian threat to use nuclear weapons as a deterrent to conventional war threatens an action that, according to nuclear warfare doctrine, would provoke a nuclear strike if directed at the US or NATO.

Nukes and Ukraine

I believe that Russia’s use of tactical nuclear weapons in Ukraine would achieve no military objective. It would contaminate territory that Russia claims as part of its historic empire, and would likely seep into Russia itself. That would increase the likelihood of direct NATO intervention and destroy Russia’s image in the world.

Putin aims to prevent Ukraine’s continued gains in regaining territory by preemptively annexing regions in the east of the country after holding rigged referendums. Then he could declare that Russia will use nuclear weapons to defend the new territory as if the existence of the Russian state was threatened. But I believe this claim stretches Russia’s nuclear strategy beyond belief.

Putin has explicitly argued that his threat to use tactical nuclear weapons is not a bluff precisely because, from a strategic point of view, their use is not credible.