Acting Ukrainian Prime Minister Arseniy Yatsenyuk has accused Russia of seeking to trigger a "third World War."
In a televised cabinet meeting on Friday, Yatsenyuk accused Moscow of attempting to occupy Ukraine "militarily and politically," creating a conflict that would spread to the rest of Europe.
The Ukrainian official said Russia’s support for anti-Kiev protesters constitutes an international crime.
Interim authorities in Kiev said on Friday that army units have begun the second phase of an operation to drive out pro-Russia activists from the country’s eastern cities.
Moscow has denounced Kiev’s operations in eastern Ukraine as a "bloody crime."