A Ukrainian soldier was killed on Sunday and another was seriously injured in a series of armed robberies in Russia, as violence escalates in the eastern part of the country.
Regarding the reported attacks, Ukraine says 27 soldiers have been killed in the east this year, more than half of the total number of people killed in 2020.
Attacks have intensified in recent weeks and Russia has built troops on the Ukrainian border.
British SKY News recorded a post in the Voronezh region of Russia, near the border. He said a small camp had been set up near the Maslovka railway station, where soldiers and equipment were arriving.
From there, they were transferred to a nearby training ground, where a military camp had been established.
SKY said the camp stretched for about a mile and a half, or about two and a half miles.
The construction of the military has raised serious concerns in the West.
United States Secretary of State Antony Blinken warned in a conversation Sunday about the "consequences" if Russia would act "violently" against Ukraine, at a time when there is an increase in Russian troops on the border with the Soviet republic.
"President Biden was very clear on this. If Russia acts recklessly, or violently, it will cost, there will be consequences," Blinken said.
In recent weeks fighting has intensified between Ukrainian troops and separatists supporting Russia in the east of the country, with signs of Russia's military formation in the region raising concerns about a major escalation in the long-running war.
Ukraine accuses Russia of mobilizing thousands of troops on its northern and eastern borders and on the Crimean peninsula.
The Kremlin, which did not deny military action, said on Sunday it would not go to war with Ukraine - but also that it "would not remain indifferent" to the fate of Russian speakers in the war-torn region.
The White House this week said the number of Russian troops on the Ukrainian border is now greater than at any time since 2014, when the conflict erupted after Russia's annexation of Crimea from Ukraine.
The conflict in eastern Ukraine has claimed the lives of more than 13,000 people and has become a nightmare for Moscow-West relations.
Fighting has subsided over the past few years but a political solution to the situation in the eastern regions has not been found.
Crimea is still considered part of Ukraine by the United Nations, and Kiev promises to one day repeat it.
Biden, who has been monitoring Washington's policies in Ukraine, is regarded as a strong ally of the Ukrainian people and his attorney general Blinken, in talks this week with his French and German counterparts, agreed to support Ukraine's "Russian invasion".