The announcement came after the Ukrainian border guards refused to surrender the tiny Snake Island in the Black Sea to a Russian warship before attacking them.
Ukraine is officially going to pay tribute to a group of Ukrainian border guards who died this week while defending Snake Island, a small Ukrainian maritime area in the Black Sea. According to Ukrainian President Volodymyr Zelensky, a Russian warship was bombed by soldiers.
Russia's invasion of Ukraine has continued since the invasion of the country on 24 February, with troops moving north, south and east. The details of the attack and the war vary from day to day, but it is the first major land conflict in Europe in decades - and hundreds of people have already been killed or injured, including more than 100 children.
Ukraine's military says on social media that a civilian ship was "sent to the island to conduct a humanitarian mission to help the victims" after the initial Russian attack - but officials claim the occupants were "illegally captured" by the Russians.