Citing Russia threat, Ukraine boosts security at ports, power plants

Ukraine's President Petro Poroshenko (R, front) attends a ceremony to hand over aircraft military equipment at an airbase of the 40th Tactical Aviation Brigade of the Ukrainian Armed Forces in Vasylkiv near Kiev, Ukraine December 1, 2018. Mykola Lazarenko/Ukrainian Presidential Press Service/Handout via REUTERS

KIEV (Reuters) - Ukrainian President Petro Poroshenko said on Saturday his country had stepped up security at vital infrastructure sites such as nuclear power stations and Black Sea ports in the face of what he called a Russian test of the world order.

Russia opened fire on and seized three Ukrainian navy ships and their crews on Nov. 25 in an incident which Moscow and Kiev have blamed on each other, triggering a crisis that has raised fears of a wider conflict.