Ukraine raised the alarm over the increase in Russian forces near its eastern border as violence flared along the line of contact separating its troops from Russia-backed separatists in the troubled Donbass region.
A German government spokesman said: “The Chancellor demanded that this build-up be unwound in order to de-escalate the situation.”
Russia has said its forces pose no threat and are defensive but insisted they would stay there as long as Moscow saw fit.
The Kremlin said Mr Putin had “noted provocative actions by Kiev which is is deliberately inflaming the situation along the line of contact”.
Ukraine’s President Volodymyr Zelenskiy flew to eastern Donbass in a show of support today two days after he called on NATO to lay out a path for Ukraine to join the military bloc, whose expansion Moscow fiercely opposes.
A senior Kremlin official said Moscow could be forced to defend its citizens in Donbass and that major hostilities could mark the beginning of the end of Ukraine as a country.
READ MORE: Russia deploys ‘Doomsday Nuke’ in Arctic military build-up
Dmitry Kozak, the deputy head of Russia’s presidential administration, said Ukraine’s government were like “children playing with matches”.
He said: “I support the assessment that the start of military action – this would be the beginning of the end of Ukraine.
Mr Kozak was asked if Russia would protect its citizens in eastern Ukraine.
In his reply her referenced Srebrenica, where about 8,000 Muslim men and boys were killed by Bosnian Serb forces during Bosnia’s 1992-1995 war.
He said: “It all depends on the scale of the fire. If there is, as our president says, ‘Srebrenica’, apparently we will have to step in to defend them.”
The Defence Ministry said today it was moving more than 10 navy vessels, including landing boats and artillery warships, from the Caspian Sea to the Black Sea to take part in the exercises.
A spokesman said: “As part of the winter training check, more than 10 amphibious and artillery boats and vessels of the southern military district are conducting an inter-fleet move from the Caspian Sea to the Black Sea.”
Russia’s Black Sea fleet is based in Crimea, which Russia annexed from Ukraine in 2014.
Kremlin spokesman Dmitry Peskov said Russia had to be cautious towards its “restless” neighbour.