Former vice president Joe Biden's presidential campaign attacked Sen. Bernie Sanders (I., Vt.) for his comments defending the late Cuban dictator Fidel Castro.

The Biden campaign released a statement Monday about Sanders calling criticism of the Communist regime "unfair" in an interview with CBS's 60 Minutes. "Make no mistake," the campaign said, "Bernie Sanders's comments on Fidel Castro are a part of a larger pattern throughout his life to embrace autocratic leaders and governments across the globe."

The statement noted Sanders's history of praising Communist regimes during the Cold War. "He seems to have found more inspiration in the Soviets, Sandinistas, Chavistas, and Castro than in America," the statement said. "His admiration for elements of Castro's dictatorship or at least willingness to look past Cuba's human rights violations is not just dangerous, it is deeply offensive to the many people … that have fled political persecution and sought refuge in the United States."

The Biden campaign added that Sanders's "ideology blinds him to the realities of life in [Communist] countries."

The attack on Sanders comes as the Vermont senator has supplanted Biden as the Democratic presidential frontrunner after strong showings in Iowa, New Hampshire, and Nevada. Biden's presidential run depends on the Feb. 29 South Carolina primary, but Sanders has begun to make in-roads in a state where Biden once enjoyed a commanding lead in the polls.

Sanders told 60 Minutes he opposes Cuban authoritarianism but said "it's unfair to simply say everything is bad, you know? When Fidel Castro came into office, you know what he did? He had a massive literacy program. Is that a bad thing?"

Sanders has previously praised Castro's Cuba during the Cold War, saying he was "very excited and impressed by the Cuban Revolution" and that while Cuba wasn't "perfect," it "solved some very important problems." Experts estimate the Castro regime is responsible for the deaths of between 35,000 and 141,000 Cubans.

Biden expressed opposition to the Castro regime as a senator. When Castro resigned from office in 2008, Biden said the United States "should not consider lifting the embargo until Cuba frees political prisoners, respects human rights, and allows independent civil organizations." But as vice president, Biden praised Barack Obama's decision to lift the Cuban embargo in 2015 without the Communist regime making any concessions on human rights.

Later Monday Biden continued to make the case for his national security experience, telling an audience in South Carolina about his role in negotiating the Paris Climate Accord signed by the Obama administration in 2016.

"I’m the guy that came back after meeting with Deng Xiaoping and making the case that I believe China would join if we put pressure on them," Biden said. Deng, who ordered the military response to the 1989 Tiananmen Square student protests, died in 1997 at 92 years old.