Russian President Vladimir Putin's nuclear threats gained momentum over the weekend when he announced that he had struck a deal with Belarusian strongman Alexander Lukashenko to station tactical nuclear weapons in Belarus.

This is the first time since the mid-1990s that Moscow will base arms outside the country. In his televised statement on Saturday, Putin also said Russia will have completed the construction of a storage facility for these weapons in Belarus by July, although he did not specify when the transfer of weapons would take place.

Concerns over growing nuclear tensions between Russia and the US have reemerged, with Russia recently suspending participation in the US-Russian New START agreement  on nuclear arms reduction. Shorthand for Strategic Arms Reduction Treaty, the deal caps the number of strategic nuclear weapons each country may have, but does not specify numbers for smaller tactical nuclear weapons.

While there have been no confirmations on the current number of Russia's tactical nuclear weapons, according to a Reuters report, Washington believes Russia has around 2,000 such working tactical warheads, which is approximately 10 times more than the US.

'Russia not preparing to use a nuclear weapon'

In response, the US has said there have been no indications that Russia was preparing to use nuclear weapons, but that they would continue to monitor the situation.

"We have not seen any reason to adjust our own strategic nuclear posture, nor any indications Russia is preparing to use a nuclear weapon," the US State Department said, adding that "we remain committed to the collective defense of the NATO alliance."

Bruno Lete, senior fellow for security and defense at the German Marshall Fund of the United States, told DW that Putin's announcement comes as no surprise to Europe and NATO.

"First of all, this is part of a larger trend in the past year where Russia has stepped up its nuclear rhetoric, and NATO and Europe are prepared," he said.

"But after Russia suspended the new Strategic Arms Reduction Treaty, worries persist that Russia could deploy nuclear weapons without any verification systems. This isn't great for peace and security and it would be better if this treaty was still in place," he added. 

What are tactical nuclear weapons?

Tactical nuclear weapons are used for specific targets in the battlefield and can replace conventional warheads in common weapon systems. They cannot detonate by themselves, but require a delivery system like Iskander missiles — short-range ballistic missile systems which Russia has used to launch conventional warheads in Ukraine and Syria.

"Tactical nuclear weapons are launched purely for winning a battle, and are not designed to attack a city. They're smaller warheads and can be up to 100 kilotons depending on the target," William Alberque, director of the strategy, technology and arms control division at the International Institute for Strategic Studies, told DW.

By comparison, strategic nuclear weapons are intercontinental and have the capacity to destroy an entire city.

"These weapons can be fired or delivered from, let's say for example, Russian territory to hit US territory. So back in the Cold War, for a warhead to be considered strategic, they would say that it should have the capacity to be launched from Siberia to Montana. They're more than 100 kilotons, or at least five times the size of the Hiroshima-Nagasaki bombs, and can cause a lot of damage," Alberque said.

How does this affect nonproliferation agreements?

The Treaty on the Non-Proliferation of Nuclear Weapons (NPT)limits the spread of nuclear weapons to non-nuclear powers. In his Saturday statement, Putin argued that stationing tactical nuclear weapons in Belarus was not in breach of this this agreement.

"There is nothing unusual here either: The United States has been doing this for decades. They have long placed their tactical nuclear weapons on the territory of their allies," Putin said according to Russia's state-owned TASS news agency.

Under the Non-Proliferation treaty, the United States, Russia, China, France and Great Britain have the right to nuclear weapons. While they cannot transfer nuclear weapons or technology to a non-nuclear power, they can deploy weapons outside their borders. Putin has highlighted that Russia would retain control over the weapons deployed, in line with nonproliferation agreements.

The US has currently deployed nuclear weapons to Europe in countries like Belgium, Germany, the Netherlands and Italy.

Maintaining weapons within sphere of control

Stefan Scheller, an associate fellow in the German Council on Foreign Relations' Security and Defense Program, highlighted that the US decision to deploy a number of nuclear weapons to some locations in Europe was part of NATO's collective defense strategy.

"There is a NATO concept called 'nuclear sharing.' This is a longstanding policy of nuclear deterrence that ensures that the benefits, responsibilities and risks of nuclear deterrence are shared across the alliance. It aims to guarantee the security of its allies," he said.

Alberque shared a similar view and said the tactical weapons owned by the US are purely designed to target troop formations or critical military infrastructure points like military headquarters of command-and-control centers. "They're not designed as strategic weapons designed to hit Moscow or St. Petersburg or something like that," he said.

With respect to Putin using Belarus as a launch pad for tactical nuclear weapons, Scheller highlighted that the decision was unilaterally announced by Putin, and not during a press conference with the Belarusian president. 

"This is a clear sign that Belarus is losing more and more national sovereignty," he said.

Over the past few years, Lukashenko has bolstered ties with Putin, helping him maintain a stronghold in Minsk amid widespread protests calling for his resignation. In 2022, he also held a referendum after which a new constitution ditching the country's non-nuclear status was approved.

How should NATO respond?

According to Lete of the German Marshall Fund of the United States, Russia deploying tactical nuclear weapons in Belarus means it could launch a strike on NATO territory far more quickly than before.

"The response time for NATO to act will be [shorter]," he said. "So, NATO either continues nuclear deterrence, which the alliance is already doing, or NATO can engage in nuclear coercion, where it engages with Russia to discourage it from deploying weapons to Belarus. But under the current situation, I think NATO will continue nuclear deterrence," he added.

Edited by: Maren Sass