Moscow has vowed to “take extra measures” if NATO sends forces to Ukraine as tensions near boiling point. Russia has already deployed about 4,000 troops to the disputed border with its neighbour, in what has been perceived by Kiev as military aggression by Vladimir Putin.
Videos and pictures taken in the disputed Donbass region show an increasing Russian military presence in the area.
Dozens of military helicopters have been spotted close to the frontier, alongside the movement of tanks and other military vehicles by train and road towards the Ukrainian border.
US military also estimated 4,000 additional troops have been sent to the border.
In response, Kiev has put its forces on high alert with drills close to Luhansk and Russian-held Crimea.
They claim they are responding to visible aggression by Russia.
Dmitry Peskov, President Putin’s spokesman, did not deny the deployment of new soldiers to the region when asked by a Ukrainian reporter.
He said: “The Russian Federation moves troops within its own territory at its own discretion, and this shouldn’t concern anyone, as such actions do not endanger anyone.”
The spokesman added that the measures were about securing its border.
JUST IN: Von der leyen hails from ‘closest thing EU has to aristocracy’
“Of course, this would call for additional measures from the Russian side to ensure its security.”
The Pentagon has told reporters that it was concerned by the reports of troop deployments and was trying to get some clarity from Moscow on the reason for them.
Ukraine’s President Volodymyr Zelensky has accused Russia of “muscle-flexing” and escalating tensions in Ukraine’s eastern regions.
He said: “Muscle-flexing in the form of military exercises and possible provocations along the border is a traditional Russian affair.”
Tensions have existed between the two nations for years, especially since Russia’s annexation of Crimea from Ukraine in 2014.
Skirmishes have been taking place between Ukrainian troops and pro-Russian separatists in Donbass.
The ongoing fighting, mixed with periods of cease-fire, is believed to have killed around 14,000 people.