Ukraine says three of its soldiers have been killed and seven wounded in the east over the past 24 hours, following two days when no fatalities were reported.
The military said on February 27 that fighting with pro-Russian separatists had halted along most of the frontline but that there were still clashes in villages around Donetsk airport.
President Petro Poroshenko earlier said that a "military threat from the east" will remain even if a cease-fire holds between government troops and rebels.
The warning was seen as a reference to Russia, which Kyiv and the West accuse of helping the separatists with weapons and soldiers -- a claim denied by Moscow.
The two sides say they are withdrawing their heavy weapons from the front line under a truce deal signed in Minsk earlier this month.
But the process is yet to be officially confirmed by international monitors.