Sen. John McCain returned from a trip to Ukraine on Sunday, calling for "a fundamental re-assessment" of the United States' relationship with Russian Vladimir Putin.

“No more reset buttons," McCain told Candy Crowley on CNN's "State of the Union." “No more reset buttons, no more ‘Tell Vladimir I’ll be more flexible.’ Treat him for what he is. That does not mean re-ignition of the Cold War. But it does mean treating him in the way that we understand an individual who believes in restoring the old Russian empire.”

McCain, who has been critical of the Obama administration's response to the crisis in Crimea, said the White House should target Russia's oil exports.

"Russia is a gas station masquerading as a country,” McCain said. “It’s kleptocracy, it’s corruption. It’s a nation that’s really only dependent upon oil and gas for their economy. And so economic sanctions are important. Get some military assistance to Ukrainians, at least so they can defend themselves. Resume the missile defense system in Poland and the Czech Republic. Look at Moldova and Georgia, both of whom are occupied by Russian troops as we speak, a path toward membership in NATO.”