Ukrainian President Petro Poroshenko said on Monday that Ukraine was facing a precarious year struggling to fend off what he called Russian strategies to undermine Kiev's attempts to pursue closer relations with Europe.
He spoke at a ceremony in central Kiev to mark 24 years of Ukrainian independence since the fall of the Soviet Union, before traveling to Berlin for talks with the leaders of France and Germany on the implementation of a much-violated cease-fire deal with pro-Russian rebels holding parts of eastern Ukraine.
"We have to get through the [coming] 25th year of independence as if on brittle ice. We must understand that the smallest misstep could be fatal. The war for Ukrainian independence is continuing," he said, addressing a crowd of several thousand.
He said 50,000 Russian troops were massed along the Ukraine-Russia border and a further 9,000 were supporting pro-Russian rebels in separatist territories. New military convoys had been tracked crossing the border into Ukraine last week, he added.
While the threat of "full-scale military invasion" remains, Russia "also has an alternative strategy — to undermine the situation in the middle of our country and to put the country at loggerheads with key [foreign] partners, isolating it with the aggressor," he said.
Russia, which annexed Ukraine's Crimea Peninsula last year after an uprising toppled pro-Russian Ukrainian President Viktor Yanukovych in Kiev, has dismissed accusations by NATO and other powers that it has sent arms and troops to back separatists in the east.
Both sides have withdrawn large numbers of heavy weapons from the conflict zone in line with February's Minsk peace agreement, but sporadic clashes still take a steady toll of lives daily.
Russia should "stop playing with agreements," Poroshenko said at a diplomatic gathering after his appearance at the Independence Day parade.
"If they do not, the reaction of the international community should be immediate and resolute. These are the messages I will take to my talks in Berlin."
Last week, Russia said German Chancellor Angela Merkel and French President Francois Hollande should put pressure on Poroshenko to stick to Ukraine's commitments under the Minsk agreement.
More than 6,500 people have been killed since fighting erupted in April 2014.