Belarus, which hosts Russian nuclear weapons, said on Monday its armed forces had begun training on how to deploy them in the field.
"During the training, in cooperation with the Russian side, it is planned to practice the delivery of nuclear munitions and their preparation for use," the Belarusian Defense Ministry said in a statement.
It said the exercise would test the military's readiness to deploy nuclear weapons in different areas of the country.
"The emphasis will be on practicing stealth, movement over significant distances, and calculations for the use of forces and equipment," the ministry said.
Belarus shares borders with Russia, Ukraine, and three NATO states.
Belarusian President Alexander Lukashenko agreed in 2023, a year after Russia's invasion of Ukraine, to host Russian tactical nuclear missiles. Russian President Vladimir Putin has made clear that Moscow retains control of their use.
Throughout the conflict, Putin has issued reminders of Russia's nuclear might that the West has seen as warnings not to intervene too deeply in support of Ukraine.
Last week, Putin said that Russia would deploy its new Sarmat nuclear missile by the end of the year, and that Moscow would continue to modernize its nuclear forces.
Belarus said the current exercise was not aimed against any other state and did not pose security threats in the region.
Kremlin dismisses Zelensky warning on Russian threat to NATO from Belarus
The Kremlin said on Monday that Ukrainian President Volodymyr Zelensky's assertion that Russia was considering an attack on a NATO country from Belarus did not deserve a response from Russia.
Kremlin spokesman Dmitry Peskov said the allegation was an attempt to escalate the situation.