Former secretary of state Hillary Clinton embraces Henry Kissinger, also a former secretary of state, as he presents her with an award from the Atlantic Council in Washington on May 1, 2013. (Jonathan Ernst/Reuters)

A former secretary of state had a star turn in the PBS Newshour Democratic debate on Thursday night. No, I don’t mean Hillary Clinton – rather, it was Henry Kissinger, who served as America’s top diplomat under Presidents Nixon and Ford.

Sen. Bernie Sanders (Vt.) took Clinton to task for being close to her predecessor. “In her book and in this last debate, she talked about getting the approval or the support or the mentoring of Henry Kissinger,” the senator said. “Now I find it rather amazing, because I happen to believe that Henry Kissinger was one of the most destructive secretaries of state in the modern history of this country. I am proud to say Henry Kissinger is not my friend.”

"I am proud to say that Henry Kissinger is not my friend," said Bernie Sanders during the PBS NewsHour democratic debate. He criticized rival Hillary Clinton for her positive comments about him, saying, "I will not take advice from Henry Kissinger." (PBS NewsHour)

Clinton defended her ties to Kissinger. “I listen to a wide variety of voices who have expertise in various areas,” Clinton responded, and went on to praise Kissinger’s efforts in Asia. “His opening up China and his ongoing relationship with the leaders of China is an incredibly useful relationship for the United States of America… Yes, people we may disagree with on a number of things may have some insight, may have some relationships that are important for the president to understand in order to best protect the United States.”

Sanders is correct that Clinton praised Kissinger in her 2014 diplomatic memoir, “Hard Choices.” In it, she describes being fascinated by Nixon’s trip to China in 1972. “Bill and I were law students without a television, so we went out and rented a portable set with rabbit ears,” she wrote. “We lugged it back to our apartment and tuned in every night to watch scenes from a country that had been blocked from view for our entire lives.” Clinton highlights Kissinger’s efforts in negotiating the trip ahead of time with Chinese authorities. “I have joked with Henry that he was lucky there were not smartphones or social media when he made his first secret trip to Beijing,” she wrote. “Imagine if a secretary tried to do that today.” (I can only imagine if we had to talk about Henry Kissinger’s emails, too.)

In the fall of 2014, Clinton also reviewed Henry Kissinger’s latest book, “World Order,” for The Washington Post, offering a largely sympathetic view. She hailed the book as “vintage Kissinger, with his singular combination of breadth and acuity along with his knack for connecting headlines to trend lines.” She also seems comfortable with his overall vision of the challenges facing the United States, writing that “his analysis, despite some differences over specific policies, largely fits with the broad strategy behind the Obama administration’s effort over the past six years to build a global architecture of security and cooperation for the 21st century.”

Predictably, the review became something of a recap of Clinton’s tenure as secretary of state and of the Obama administration’s foreign policy accomplishments, with some quotes from Kissinger’s book sprinkled in. (No surprise: That’s often what happens when big-name former officials write book reviews.) But she also offers an unusual interpretation of Kissinger’s foreign-policy vision. “For an international order to take hold and last, Kissinger argues, it must relate ‘power to legitimacy.’ To that end,” Clinton writes, “Kissinger, the famous realist, sounds surprisingly idealistic. Even when there are tensions between our values and other objectives, America, he reminds us, succeeds by standing up for our values, not shirking them, and leads by engaging peoples and societies, the source of legitimacy, not governments alone.”

She does, however, include a passage that highlights not only their friendship but her trust in Kissinger’s insights:

Kissinger is a friend, and I relied on his counsel when I served as secretary of state. He checked in with me regularly, sharing astute observations about foreign leaders and sending me written reports on his travels. Though we have often seen the world and some of our challenges quite differently, and advocated different responses now and in the past, what comes through clearly in this new book is a conviction that we, and President Obama, share: a belief in the indispensability of continued American leadership in service of a just and liberal order.

Sanders finished his attack on the Clinton-Kissinger ties declaring that, as president, “I will not take advice from Henry Kissinger.” It’s not clear Clinton would make the same promise.

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