Sen. John McCain (R-AZ) on Tuesday suggested that President Barack Obama's handshake with Cuban President Raul Castro was like shaking hands with Adolf Hitler.

At the memorial service for former South African President Nelson Mandela, the U.S. president briefly greeted Castro moments before taking the stage to note that "too many who claim solidarity with Madiba’s struggle for freedom but do not tolerate dissent from their own people."

Public Radio International correspondent Todd Zwillich caught up with McCain in Washington, D.C. later in the day and asked him about the unplanned meeting.

"It gives Raul some propaganda to continue to prop up dictatorial, brutal regime, that's all it is," the Arizona Republican insisted. "Why should you shake hands with somebody who's keeping Americans in prison?"

"I mean, what's the point?" he added. "Neville Chamberlain shook hands with Hitler."

British Prime Minister Neville Chamberlain's 1938 handshake with Hitler is often seen as symbolic of the European policy of avoiding war with dictatorships through appeasement.

But it's not the first time President Barack Obama has been compared to Chamberlain. As recently as last month, The Washington Times called the president "Barack Neville Chamberlain Obama" for a deal that will freeze Iran's nuclear enrichment program for six months.

Sen. Ted Cruz (R-TX) concluded earlier this year that funding the president's health care reform law was also similar to appeasing Hitler.