A Ukrainian soldier was killed and another wounded in fighting with pro-Russian separatists in the east of the country, Ukraine's army said.
The wounded soldier was hospitalised but his life is not in danger, it added.
The death brings the total number of Ukrainian soldiers killed on the frontline this year to 65, up from 50 the previous year, according to AFP's assessment based on official information.
The Ukrainian army has accused separatists of firing on its positions with 82-millimetre mortars and grenade launchers.
It comes as tensions between Kyiv and Moscow are at a level unseen since the illegal annexation of the Crimean peninsula in 2014 with Russia accused of preparing an invasion. US intelligence estimates that 100,000 Russian troops are currently stationed along the border with Ukraine.
Moscow denies that it has any warlike intentions and accuses Ukraine of posing a "threat" to it and NATO of wanting to expand to its borders.
NATO and the European Union warned Moscow on Thursday of "massive consequences" if it intervenes militarily in Ukraine, after rejecting Russia's wish to veto Kyiv's possible membership of the alliance.
Eastern Ukraine has been at war with separatists since 2014, with Moscow widely seen as the military sponsor, despite its denials.
The conflict, which has left more than 13,000 people dead, broke out shortly after Russia annexed Crimea.