, the latest turn in a crisis between the two neighbors after Russia seized three Ukrainian ships earlier this week.
Russian coast guard ships on Sunday fired on and seized the Ukrainian vessels as they headed toward a contested strait close to Crimea, taking prisoner 24 Ukrainian sailors and triggering an international crisis.
Petro Tsygykal, Ukraine's chief of Border Guard Service, told a security meeting that all Russian males between 16 and 60 will be barred from travelling to Ukraine for the duration of martial law, which Ukraine's parliament voted to introduce on Monday for 30 days in some regions.
"At checkpoints, reinforced control measures are being implemented. Today, the entry of foreigners, especially citizens of the Russian Federation, is limited," Tsygykal said at the meeting, according to a published transcript on the website of Ukraine's presidential office.a