Simferopol, Ukraine (CNN) -- Demonstrators clapped along to Soviet-era songs as dancers from Russia's Black Sea fleet entertained the masses at the center of Crimea's administrative capital Sunday. But it was more than just nostalgia for the old Soviet Union. With a controversial referendum over whether Crimea will remain part of Ukraine just a week away, it was a rallying cry for ethnic Russians gathered in Simferopol's Lenin Square. The large demonstration was the latest flashpoint as tensions simmer on the Crimean peninsula, which has become the epicenter of a battle for influence among Moscow, Kiev and the West since Ukrainian President Viktor Yanukovych's ouster last month.
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Pro- and anti-Russian groups hold rival rallies in Crimea
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Putin speaks with British PM, German Chancellor about the situation there
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CNN analyst: Putin is "very worried by the situation"
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The Ukrainian prime minister is expected to arrive in the United States on Wednesday
@placeholder also said new Ukrainian authorities were doing nothing "to curb ultra-nationalist and radical forces committing outrages" in Kiev and other regions.