Russian President Vladimir Putin on Saturday visited Crimea, the Ukrainian peninsula Moscow annexed in 2014, a trip quickly denounced by Kiev as a violation of Ukraine's sovereignty.
Putin made a stop at the legendary Artek holiday camp for young people, dating from Soviet times, on the shores of the Black Sea, the Kremlin said in a statement.
Founded in 1925 based on an idea from Lenin, the father of Russian communism, Artek went from a sanitorium for children with tuberculosis to a camp for "pioneers", the communist youth organisation for children aged 10 to 14.
After the collapse of the Soviet Union in 1991, Artek, like all of Crimea, was part of an independent Ukraine and the facility fell on hard times. But after the Russians took back the peninsula the youth camp was renovated.
"It wasn't that long ago that Artek went through rather difficult times. But now it is being reborn, and it is reborn as an international holiday camp," Putin said in a speech to the young people.
Putin has visited Crimea before since Russia's annexation, which was condemned by the international community, and Kiev considers it to still be part of Ukraine.
The country's foreign ministry issued a statement saying Kiev "considers this visit... to be a gross violation of the sovereignty of the State and the territorial integrity of Ukraine," according to the Russian TASS news agency.
Ukraine has been fighting a pro-Russian insurgency in the east of the country since 2014 which Kiev and its Western allies say is backed by Moscow. More than 10,000 people, civilians and fighters, have been killed since the start of the conflict.