Russian paratroopers from the Moscow Airborne Guards Unit are in Belarus, Interfax reports, citing the press service of the Russian Defense Ministry.
On Thursday, together with their Belarusian colleagues, they conducted exercises to practice storming a building at the test site near Brest.
Russian servicemen parachuted out of the Mi-8 MTV-5 helicopter, stormed, freed the hostages and cleared the building seized by a hypothetical enemy.
The "urban assault" is "one of the most difficult exercises," the Defense Ministry said, adding that the exercises took place under heavy rain and strong gusty winds.
The exercises took place as part of the Army International Polar Star Competition, which kicked off in Belarus on Sunday, August 23, at the height of mass protests, when more than 200,000 people took to the streets across Belarus.
The day before, Russian President Vladimir Putin announced the formation of a "reserve" of law enforcement officers who can be sent to Belarus to help Alexander Lukashenko, who is facing the worst political crisis in 26 years.
The reserve was created at Lukashenko's request, Kremlin spokesman Dmitry Peskov said on Friday.
This was done "in accordance with the obligations that are spelled out for Russia in two treaties: the Collective Security Treaty and the Treaty on the Union State," Peskov said, adding that Russian units "in case of extreme necessity can prevent extremist actions in the republic."
Peskov refused to specify the size of the reserve and its composition: whether it includes only employees of the Russian National Guard, or even the military.
"Russia has not interfered, nor does it interfere in the internal affairs of Belarus," he said, adding that the Kremlin assumes that Belarus "will not face" a situation where Russia's military assistance is needed.