An analyst for a international think tank in Tallinn says the situation on the ground in eastern Ukraine is turning into a low-intensity asymmetric conflict of the type seen in the former Yugoslavia or the war between Georgia and Abkhazia in the 1990s.
Kaarel Kaas, who edits Diplomaatia magazine for the International Center for Defense Studies, said that although government forces have made headway in recent weeks, the eastern part of the county is still a chaotic battleground.
"Although the separatist side has long used heavy weaponry and their units are supported by the Russian standing army from behind the border, also with heavy weaponry and long-range fire, this is not a classic regular army vs regular army conflict with mechanised and motorised units."
Why have Ukrainian forces managed to post successes only now? One reason is psychological, Kaas says.
"At first, the entire situation for Ukrainian government forces was so shocking, unexpected and unaccustomed that psychologically they were not ready for battle. They didn't want to fire at people they assumed were also their compatriots. But that psychological barrier was finally broken."
And, said Kaas, Ukraine firmed up its resolve against the separatists, establishing a clearer, more coordinated chain of command. Ukrainian troops gained combat experience and volunteers who helped boost the military ranks also helped lift morale.