Russian forces stormed two Ukrainian bases and seized ships and other military assets at the weekend as Moscow moved swiftly to stamp its authority on Crimea, which it formally annexed last week.

On Saturday afternoon Russian armoured vehicles crashed through the walls of the Belbek base near Sevastopol and troops fired shots and detonated stun grenades to subdue about 200 poorly armed Ukrainian troops there who had defied an ultimatum to surrender. A Ukrainian defence ministry liaison was unable on Sunday to confirm a report that Yuliy Mamchur, the base’s commanding officer, had been detained.

Ukraine’s defence ministry said that Russian forces and pro-Russian Crimean “self-defence” units on Saturday also seized a naval aviation base at Novofedorivka in western Crimea, where as of Sunday afternoon Russian forces could be seen stationed inside.

Separately pro-Russian forces seized the Slavutich, a Ukrainian warship anchored in the port of Sevastopol, Vladimir Seleznev, spokesman for Ukraine’s defence ministry, wrote on his Facebook page. The ship raised the Russian flag on Saturday night, following at least three others based in Crimea’s main military port reported to have switched to Russian control in recent days.

Also on Saturday Ukrainian forces surrendered the Zaporizhia, Ukraine’s last remaining submarine, to Russia, after its naval forces surrounded the vessel.

Ihor Teniuk, Ukraine’s defence minister, said that a decision about withdrawing some Ukrainian forces from Crimea would be taken in the near future.

“In Crimea the seizure of ships has been carried out,” Mr Teniuk said in comments quoted by the Interfax news agency. “Despite the fact that all the commanders had orders to use weapons, the commanders did not use these weapons so that there would be no bloodshed.”

At the Belbek base, too, Ukraine’s vastly outgunned troops, some of whom were armed with sticks, put up only a symbolic resistance. After masked Russian ‘self-defence’ troops stormed the base, they turned their backs on them to face Mr Mamchur and sing the Ukrainian national anthem, before Mr Mamchur was taken away for talks with a Russian official. A crowd of people massed on the streets outside cheered when the armoured vehicles breached the base’s walls, and chanted “Rossiya, Rossiya” as they watched the operation.

Russia will provide a corridor to evacuate Ukrainian troops, thought to number about 10,000, who want to return to the mainland, Sergey Aksenov, Crimea’s pro-Russian leader, says.

Russia’s actions at the weekend eliminated most remaining resistance in Ukraine’s military to its annexation of the territory, which President Vladimir Putin formalised in a law he signed on Friday.

However, three Ukrainian ships remain blocked inside Donuzlav Lake, an inlet in western Crimea near the town of Mirny. Their commanders have been obstructed by Russia’s navy from leaving a narrow opening joining the lake to the sea. Ukraine wants to remove the ships to the port city of Odessa to reconstitute its own depleted navy there.

On Sunday, three grey Russian warships were positioned on the Black Sea side of Donuzlav lake; on the inland side of the inlet were visible three Ukrainian warships – the largest of them the Konstiantyn Olshansky, whose resistance to Russian capture has taken on a near-mythic status in Ukraine.

Picnickers and a few western journalists watched the stand-off on Sunday. Aleksander Braun, a self-described entrepreneur drinking a beer alongside his car with two friends, expressed doubts that the men of the Olshansky would succeed in holding out.

“They’re stuck without any support,” he said. “They don’t’ have enough fuel, and they don’t have enough to eat.” Describing himself as Ukrainian, Mr Braun said he disagreed with the narrative in the west that Russia was grabbing Crimea against its people’s will. “We want to go to Russia,” he said, dismissing the authority of the government in Kiev. “They’ve lost power.” Aleksey Dudchenko, Mr Braun’s friend, gazed at the Ukrainian ships through a pair of binoculars. “I think everyone will come to shore and give up,” he said.

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