Ukraine has lost nearly all the warships it had in the Crimean Peninsula and the government on Sunday ordered the crew of the huge landing ship Konstantin Olshansky, which is under siege by Russian troops, to resist until the end.
"The navy ships in Crimea have been taken. Despite the fact that commanders were given orders to use their arms, they did not use them to avoid bloodshed," Ukrainian Defence Minister Igor Teniuj said.
The Konstantin Olshansky and the minesweeper Cherkassy were the last Ukrainian ships to ignore orders to surrender from the Russian military in the waters of Donuzlav Bay. Russian forces sank two Ukrainian vessels, preventing the two warships from escaping.
The Konstantin Olshansky went on full combat alert on Sunday after boats carrying Russian marines approached.
"Olshansky has all its armaments and the sailors have firearms," Teniuj said in response to media reports that the crew was unarmed.
Russian President Vladimir Putin and the leader of the breakaway Ukrainian region of Crimea signed a pact last Tuesday making the Black Sea peninsula part of Russia again.
The accord came after more than 96% of Crimeans who cast ballots in last Sunday's referendum on rejoining Russia voted "yes."
Ethnic Russians make up around 60% of the roughly 2 million residents of the peninsula, which then-Soviet leader Nikita Khrushchev decided to make part of Ukraine in 1954.
Moscow has deployed troops in the peninsula, claiming it was protecting ethnic Russians and Russia's interests.
The United States and its allies denounced Sunday's referendum in the Crimea as contrary to international law.