Washington (CNN) Sen. Bernie Sanders offered a partial defense of Fidel Castro's Cuban revolution, asserting that "It's unfair to simply say everything is bad" with the way the late despot ruled the country.

"We're very opposed to the authoritarian nature of Cuba but you know, it's unfair to simply say everything is bad. You know?" Sanders said on CBS' "60 Minutes" in an interview that aired Sunday. "When Fidel Castro came into office, you know what he did? He had a massive literacy program. Is that a bad thing? Even though Fidel Castro did it?"

The comments -- which could prove to alienate some moderate Democrats as Sanders' chases the party's primary nomination -- came in response to a question about remarks Sanders had made in the 1980s assessing that the Cuban people didn't rise up against Castro because of education and healthcare.

When host Anderson Cooper pointed to the notable number of dissidents imprisoned in Cuba, Sanders responded, "That's right. And we condemn that."

"Unlike Donald Trump, let's be clear, you want to -- I do not think that Kim Jong Un is a good friend," he said. "I don't trade love letters with a murdering dictator. Vladimir Putin, not a great friend of mine."

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