A Ukrainian soldier was killed when rebels staked out in a kindergarten shelled a military checkpoint near the rebel flashpoint of Slavyansk on Monday, the defence ministry said.
Three other troops were also injured in the pre-dawn attack, which came almost a week after seven soldiers were killed in an ambush between Slavyansk and Kramatorsk, the heaviest single loss of life on the part of the military in weeks of fighting in the east of Ukraine.
"The terrorists, acting in their usual cynical and insidious manner, launched the attack from a kindergarten near the railway station," the ministry said in a statement. "They wanted to provoke the servicemen into trying to destroy the kindergarten."
Ukraine's military launched an offensive against pro-Russian insurgents in mid-April, but has failed to oust them from their strongholds in more than a dozen towns and cities.
Violence has flared almost nightly in various hotspots across the east, rattling Ukraine's plans for a presidential election on Sunday.