Tactical nuclear weapons have burst onto the international stage as Russian President Vladimir Putin, facing battlefield losses in eastern Ukraine, has threatened that Russia will “make use of all weapon systems available to us” if Russia’s territorial integrity is 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.

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

I am an international security scholar who has worked on and researched nuclear restraint, nonproliferation and costly signaling theory 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 doctrine of threatening their use have raised tensions, but tactical nuclear weapons are not simply another type of battlefield weapon.

Tactical by the numbers

Tactical nuclear weapons, sometimes called battlefield or nonstrategic nuclear weapons, were designed to be used on the battlefield – for example, to counter overwhelming conventional forces like large formations of infantry and armor. They are smaller than strategic nuclear weapons like the warheads carried on intercontinental ballistic missiles.