What’s behind Russian President Vladimir Putin’s decision to deploy tactical nuclear weapons in Belarus?

The move that Putin announced in late March would be the first time since the fall of the Soviet Union that Russia has stationed nuclear weapons beyond its own borders, and it raises the prospects for a renewed, destabilizing nuclear arms rivalry with the United States and its North Atlantic Treaty Organization (NATO) allies.

Belarus is an authoritarian state that was one of four Soviet republics to host nuclear weapons. Along with Kazakhstan and Ukraine, Belarus relinquished its nuclear weapons to Russia in the 1990s in exchange for security guarantees from Russia, the United States, and the United Kingdom (UK). Today, it is militarily allied with Russia, and it has served as a staging ground for Russian forces that invaded Ukraine from the north in early 2022.

Putin said that Belarusian President Aleksandr Lukashenko had long requested the deployment of Russian nuclear weapons and that storing them in Belarus would be akin to what the United States has been doing in Europe for decades. Tactical nuclear weapons are intended to be used against enemy forces in a theater of conflict and generally have shorter ranges and lower yields than so-called strategic weapons, which can travel thousands of miles to destroy enemy population centers. Those are mainly intended as a catastrophic deterrent and weapon of last resort.

Where in Europe does the United States have nuclear weapons?

The United States has deployed nuclear weapons at NATO bases in Western Europe since the 1950s, when Cold War tensions were mounting with the Soviet Union. The weapons were first transferred to the United Kingdom in 1954, and later to Germany, Italy, France, Turkey, the Netherlands, Greece, and Belgium.

Today, U.S. tactical nuclear weapons remain at six bases in five NATO member countries, Belgium, Germany, Italy, the Netherlands, and Turkey. The UK and France have their own nuclear forces and no longer host U.S. weapons.

How many U.S. nuclear weapons are in Europe?

The number of U.S. weapons deployed in Europe peaked at more than seven thousand in the 1970s and then dropped steeply in the late 1980s and early 1990s as a result of arms control agreements and the end of the superpower rivalry with the Soviet Union.

A major arms control success for European security came in 1987 with the now-defunct Intermediate-Range Nuclear Forces (INF) Treaty. In accordance with the INF, the United States and Soviet Union eliminated in a matter of years their entire arsenals of medium-range, nuclear-capable missiles and launchers. Prior to the INF, both countries had been ramping up their missile deployments in Europe.

Current U.S. nuclear stockpiles are classified, but security analysts estimate that the United States has about one hundred nuclear bombs stored across the six facilities in Europe.

What type of nuclear weapons are they?

The U.S. nuclear arsenal in Europe consists entirely of B61 gravity bombs [PDF], which are designed to be dropped from allied bombers or fighter aircraft. In service for more than fifty years and modernized many times, the B61 is the last remaining tactical nuclear weapon the United States has. It can carry warheads with a wide range of yields, delivering blasts into the hundreds of kilotons. By comparison, the U.S. bombs that killed more than one hundred thousand people in Hiroshima and Nagasaki, Japan, in 1945 had yields of fifteen and twenty-one kilotons, respectively.

Why are they still in Europe?

U.S. nuclear weapons were originally deployed to deter Soviet aggression, via conventional military attack or nuclear strike, and to reassure NATO allies in Western Europe. At the time, NATO members’ conventional armies were outnumbered by those of the Soviet Union and its Warsaw Pact allies. The presence of U.S. nuclear weapons on the continent was viewed as a means of making up for this deficiency in NATO forces.

However, with the end of the Cold War, many Western military strategists, peace advocates, and politicians questioned the need to keep these legacy weapons in Europe. Not only was the Soviet Union gone and NATO greatly enlarged, they said, but the United States’ strategic nuclear arsenal—including long-range bombers, intercontinental ballistic missiles (ICBMs), and submarine-launched weapons—served as a sufficient deterrent against any potential adversary, including Russia. Moreover, many defense analysts have said that allied aircraft attempting to drop the bombs would likely be shot down by sophisticated enemy air defenses.

Yet, proponents of keeping U.S. nuclear forces in Europe say these weapons continue to provide NATO with a valuable military deterrent and are an important symbol of the United States’ commitment to its allies. Withdrawing them would send a dangerous message of U.S. retrenchment to would-be adversaries in Europe and beyond, they say. Even if these weapons do have little military value, advocates say they could be used as a bargaining chip in  future diplomacy with Russia, particularly since Moscow has long pushed for their removal. Therefore, they say, the United States shouldn’t remove them without obtaining significant concessions from Russia.

Where does Russia have nuclear weapons?

Western analysts say that Russia has its nuclear forces—ICBMs, submarines, and heavy bombers—spread across more than a dozen military bases throughout its vast territory.

Meanwhile, many Western observers have questioned whether it has nuclear weapons in Kaliningrad, a Russian exclave located between NATO members Poland and Lithuania. In 2018, a Russian government official reportedly confirmed that Russia had sent nuclear-capable Iskander missiles to Kaliningrad; separately, Western researchers said Russia was upgrading a nuclear storage site there, although it remained unclear if nuclear warheads were actually present then. In April 2022, Lithuania’s defense minister said Russian nukes “have always been kept in Kaliningrad.” At the time, former Russian President Dmitry Medvedev warned that if Finland and Sweden applied to join NATO, which they subsequently did, Russia would have to restore the nuclear balance in the Baltics.