Washington for its part admitted to a "fundamental disagreement" with Russia and said President Barack Obama would meet Petro Poroshenko, whose May 25 presidential election win Moscow refuses to acknowledge, in Warsaw on Wednesday.
The months-long fight for future of the ex-Soviet nation -- splintered between a more nationalist west and a heavily Russified southeast -- has killed more than 300 people and resurrected the geopolitical barriers of the Cold War.
Ukraine's separatist insurgency only intensified after 48-year-old billionaire chocolate maker Poroshenko won 54.7 per cent of a ballot that was disrupted across swathes of the eastern rust belt.
Government forces reported suffering no casualties today while repelling two rebel attempts to recapture an airport in the eastern hub of Donetsk they had seized a day after the election at the cost of 40 fighters -- most of them Russian nationals.
Ukraine's acting foreign minister said Russia was now using every means at its disposal to unsettle the new Kiev leaders and regain control over its historic domain.
"Five days since elections, there has been no official recognition yet. Obviously, the Russian Federation doesn't have legal grounds to question the election's legitimacy," Andriy Deshchytsya wrote in an opinion piece published in the edition of the English-language Kyiv Post.
"The massive... information campaign Kremlin has launched these days, with an avalanche of doubletalk and fake news, signals one thing -- this is Russia's last chance to try shifting the balance of international public opinion," he wrote.
Russia yesterday accused Ukraine of breaching the 1949 Geneva Conventions protecting civilians in wartime by killing and wounding peaceful citizens during its seven-week "anti-terrorist operation" in the separatist industrial regions of Lugansk and Donetsk.