Sen. John McCain (R-Ariz.) predicted that Russia would hold onto Crimea and called for a "fundamental reassessment" of America's relationship with Russian President Vladimir Putin on Sunday.

McCain, who had recently returned from a trip to Ukraine, said Sunday's referendum in Crimea on whether to split from Ukraine was "a bogus thing," comparing it to the plebiscites held in the days of Hitler and Stalin. "It's a done deal," he said.

He supported economic sanctions as an important step in the U.S. response to Russia's actions.

"Russia is a gas station masquerading as a country," McCain told Candy Crowley on CNN's "State of the Union." "It's kleptocracy, it's corruption, it's a nation that's really only dependent upon oil and gas for their economy."

But he also said that wider action was necessary.