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SEVASTOPOL, Ukraine, March 19 (Reuters) - Three Russian flags were flying at an entrance to Ukraine's naval headquarters in the Crimean port of Sevastopol on Wednesday, witnesses said, as pro-Russian forces took control of at least some of the base without armed resistance.
It was the clearest sign so far that Russian soldiers, and so-called "self-defence" units of mainly unarmed volunteers who support them, had begun to take control of Ukrainian military facilities across the Black Sea peninsula.
Shortly after the incident, Ukraine's acting Defence Minister Ihor Tenyukh said in Kiev that the country's forces would not withdraw from Crimea even though Russian President Vladimir Putin has signed a treaty to make it part of Russia.
The fate of Ukrainians military personnel at the Sevastopol compound was not clear, with reporters not allowed to enter the base and only able to see small areas of it.
But local witnesses said that not a shot had been fired in anger when pro-Russian forces moved in.
A Reuters reporter saw three armed men, possibly Russian soldiers in unmarked uniforms, at the gate. Local witnesses also saw one armoured personnel carrier enter the base.
Thousands of Russian soldiers have taken control of Crimea in recent weeks in the buildup to last Sunday's referendum, in which Russian-majority Crimea voted overwhelmingly to leave Ukraine and join Russia.
Moscow denies deplying extra troops, and Russian soldiers in the region are wearing unmarked uniforms, making it difficult to verify exactly who is who on the ground. (Reporting by Aleksandar Vasovic in Sevastopol and Gabriela Baczynska and Mike Collett-White in Simferopol; writing by Mike Collett-White; Editing by Richard Balmforth)