Russia has begun moving nuclear weapons to its ally Belarus, the country’s strongman Alexander Lukashenko announced Thursday, after transfer plans were unveiled earlier this year.

The move came after Russia and Belarus signed a deal Thursday formalizing the deployment of Moscow’s tactical nuclear weapons on the territory of its ally. However, control of the weapons remains in the Kremlin.

"The transfer of nuclear munitions has begun," Lukashenko said in an official video.

Russian President Vladimir Putin announced the deployment of shorter-range weapons in Belarus in March in a move widely seen as a warning to the West as it stepped up military support for Ukraine.

When the weapons would be deployed wasn’t announced, but Putin has said the construction of storage facilities in Belarus for them would be completed by July 1.

Also unclear is how many nuclear weapons would be kept in Belarus. The U.S. government believes Russia has about 2,000 tactical nuclear weapons, which include bombs that can be carried by aircraft, warheads for short-range missiles and artillery rounds.

Tactical nuclear weapons are intended to destroy enemy troops and weapons on the battlefield. However, they have a relatively short range and a much lower yield than nuclear warheads fitted to long-range strategic missiles capable of obliterating whole cities.

Speaking in Moscow, Lukashenko said it was "possible" that the weapons were already in his country.

Lukashenko, who sparked rumors of being seriously ill when he cut short a Victory Day appearance in Red Square on May 9 before resurfacing in public on May 15, was attending a meeting of the Supreme Eurasian Economic Council with Putin and leaders of Armenia, Kazakhstan and Kyrgyzstan.

The deal’s signing came as Russia prepared for a counteroffensive by Ukraine. Russian and Belarusian officials also framed the step as driven by hostilities from the West.

"Deployment of nonstrategic nuclear weapons is an effective response to the aggressive policy of countries unfriendly to us," Belarusian Defense Minister Viktor Khrenin said in Minsk at a meeting with his Russian counterpart, Sergei Shoigu.

"In the context of an extremely sharp escalation of threats on the western borders of Russia and Belarus, a decision was made to take countermeasures in the military-nuclear sphere," Shoigu added.

‘Threat to all of Europe’

Putin has argued that by deploying its tactical nuclear weapons in Belarus, Russia followed the United States lead, noting that the U.S. has nuclear weapons based in Belgium, Germany, Italy, the Netherlands and Türkiye.

Exiled Belarusian opposition leader Sviatlana Tsikhanouskaya condemned the move.

"We must do everything to prevent Putin’s plan to deploy nuclear weapons in Belarus, as this will ensure Russia’s control over Belarus for years to come," Tsikhanouskaya told The Associated Press (AP).

"This will further jeopardize the security of Ukraine and all of Europe," she warned.

Independent Belarusian military analyst Aliaksandr Alesin said about two-thirds of Russia’s medium-range nuclear-tipped missiles were held in Belarus during the Cold War, adding that dozens of Soviet-era storage facilities could still be used.

Soviet nuclear weapons stationed in Belarus, Ukraine, and Kazakhstan were moved to Russia in a U.S.-brokered deal after the dissolution of the Soviet Union in 1991.

"Documents in Minsk on the return of nuclear weapons were defiantly signed just when Ukraine declared a counteroffensive and Western countries are handing over weapons to Kyiv," Alesin told the AP.

"This Belarusian nuclear balcony should spoil the mood for politicians in the West since nuclear missiles can cover Ukraine, Poland, the Baltic states and parts of Germany."

Khrenin also announced plans to "build up the combat potential of the regional grouping of Russia and Belarusian troops," including the transfer to Minsk of the Iskander-M missile system, capable of carrying a nuclear charge, and the S-400 anti-aircraft missile system.

Russia and Belarus have an alliance agreement under which the Kremlin subsidizes the Belarusian economy via loans and discounted Russian oil and gas. In addition, Russia used Belarusian territory as a staging ground for invading neighboring Ukraine and has maintained a contingent of troops and weapons there.