As Russia suffered unexpected losses on the battlefield in eastern Ukraine, tactical nuclear weapons burst onto the international stage. Russian President Vladimir Putin threatened that Russia “to use all the weapons systems available to us“, when the territorial integrity of Russia will be threatened. Putin described the war in Ukraine as existential struggle with the Westwho, according to him, wants to weaken, divide and destroy Russia.

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

I am an international security professional who has worked on and research nuclear deterrence, non-proliferationand expensive signaling the theory has been applied to international relations for two decades. Russia’s large arsenal of tactical nuclear weapons, which are not governed by international treaties, and Putin’s threat doctrine to use them have heightened tensions, but tactical nuclear weapons are not just another type of weapon on the battlefield.

Tactics by numbers

Tactical nuclear weapons, sometimes called battlefield or non-strategic nuclear weapons, were developed for use on the battlefield – for example, to counter superior conventional forces such as large infantry and armored formations. They are smaller than strategic nuclear weapons, such as the warheads found on intercontinental ballistic missiles (ICBMs).

While the experts differ in precise definitions For tactical nuclear weapons, commonly identified characteristics include a lower explosive yield, measured in kilotons, and a shorter delivery range. Tactical nuclear weapons range in yield from fractions of 1 kiloton to about 50 kilotons. By comparison, strategic nuclear weapons are much more powerful, with a yield of 100 kilotons to a megaton. Much more powerful warheads were developed during the Cold War, culminating in the Tsar Bomba with a yield of more than 50 megatons.

For reference, the atomic bomb dropped on Hiroshima was 15 kilotons. This means that some types of tactical nuclear weapons are capable of causing widespread destruction. The the largest conventional bombThe Mother of All Bombs, or MOAB, dropped by the US has a yield of 11 tons (0.011 kilotons).

Tactical nuclear weapon delivery systems also tend to have a shorter range, typically less than 310 miles (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 conventional weapons, which are becoming increasingly powerful, the US military has reduced its reliance on them. Most of the stock left, about 150 B61 Gravity Bombsthere is deployed in Europe. 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 2,000and relied more on them in its nuclear strategy than the US, mainly because of Russia’s less advanced conventional weapons and capabilities.

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

Russia has upgraded its delivery systems to be able to carry both nuclear and conventional bombs. There is heightened concern about these dual-capability delivery systems because Russia has used many of these short-range missile systems, particularly the Iskander-M, to bomb Ukraine.

Russia’s Iskander-M short-range mobile ballistic missile can carry conventional or nuclear warheads. Russia used missiles with conventional warheads in the war in Ukraine.

Tactical nuclear weapons are far more destructive than their conventional counterparts, even with the same blast energy. There are nuclear explosions 10-100 million times more powerful than chemical explosions, and will leave deadly radiation fallout that will contaminate the air, soil, water and food supplies, similar to the catastrophic nuclear reactor accident at the Chernobyl nuclear power plant in 1986. Interactive simulation site NUKEMAP Alex Wellerstein depicts many effects of nuclear explosions of different power.

Can any nuclear weapon be tactical?

Unlike strategic nuclear weapons, tactical weapons are not focused on mutual assured destruction through stunning retaliation or nuclear umbrella deterrence to protect allies. While tactical nuclear weapons were not included in the arms control treaty, intermediate-range weapons were included in the now defunct Treaty on medium and short-range missiles (1987-2018), which reduced nuclear weapons in Europe.

Both the US and Russia have reduced their total nuclear arsenals from approx 19,000 and 35,000 respectively at the end of the Cold War to a 3700 and 4480 as of January 2022. Russia’s reluctance to negotiate over its non-strategic nuclear weapons has stalled further nuclear arms control efforts.

The fundamental question is whether tactical nuclear weapons are more “usable” and thus potentially capable of triggering full-scale nuclear war. Their development was part of an effort to overcome concerns that, as 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 country’s nuclear deterrence.

However, any use of tactical nuclear weapons will trigger defensive nuclear strategies. In particular, then Secretary of Defense James Mattis declared in 2018: “I don’t think there are any tactical nuclear weapons. Any use of nuclear weapons at any time changes the strategic game.”

This documentary examines how the risk of nuclear war has changed – and perhaps increased – since the end of the Cold War.

The US criticized Russia’s nuclear strategy escalate to de-escalationin which tactical nuclear weapons can be used to deter an expansion of the war to include NATO.

Although there is disagreement among experts, the nuclear strategies of Russia and the United States are focused on deterrence and thus involve large-scale nuclear strikes in retaliation in the face of the use of nuclear first weapons. This means that Russia’s threat to use nuclear weapons as a deterrent to conventional war threatens actions that, according to nuclear war doctrine, would result in a nuclear retaliatory strike if targeted at the US or NATO.

Nuclear weapons and Ukraine

I believe that Russia’s use of tactical nuclear weapons in Ukraine will not achieve any military objective. It would contaminate territory that Russia claims as part of its historic empire, and possibly spill over into Russia itself. This would increase the likelihood of direct NATO intervention and destroy Russia’s image in the world.

Putin seeks to preemptively restrain further successes of Ukraine in returning the territory annexation of regions in the east of the country after holding phased referendums. Then he could declare that Russia will use nuclear weapons to defend the new territory, as if the existence of the Russian state is threatened. But I believe that this statement stretches the Russian nuclear strategy beyond belief.

Putin directly stated his threat to use tactical nuclear weapons this is not a bluff precisely because, from a strategic point of view, using them does not inspire confidence.

By Nina Srinivasan Rathbun, Professor of International Relations,[{” attribute=””>USC Dornsife College of Letters, Arts and Sciences.

This article was first published in The Conversation.