At least 20 flights from Kharkiv, eastern Ukraine’s largest city, and the regional capital of Donetsk were canceled ahead of a national holiday Friday commemorating World War II. By Monday afternoon all air traffic in the country ceased.
The moves came as interior minister Arsen Avakov announced four government soldiers and about 30 pro-Russian separatists were killed in gun battles the previous day in the eastern city of Slovyansk.
Vehicle checkpoints were established around Ukraine’s capital city, Kiev, as a precaution against attacks, acting President Oleksandr Turchynov said.
Late Monday, Germany reinforced a travel advisory, recommending German citizens leave eastern and southern Ukraine. The German Foreign Ministry also advised journalists not to travel to those areas.
The developments came as Ukraine prepared for its national holiday, as well as presidential elections scheduled for May 25. In a television interview in Paris, French President Francois Hollande warned there would be "chaos and the risk of civil war" if the elections were postponed. Tens of thousands of Russian troops are currently deployed on the border between Ukraine and Russia for what the Russian government calls training exercises.