The two high points of tonight's Democratic debate—and, as far as I'm concerned, the two high points of Bernie Sanders' presidential campaign—came when the moderators raised the topic of foreign policy. Sanders has criticized Hillary Clinton for backing the Iraq war before, but this time he used that as a springboard for larger critique:

Now I think an area in kind of a vague way, or not so vague, where Secretary Clinton and I disagree is the area of regime change. Look, the truth is that a powerful nation like the United States, certainly working with our allies, we can overthrow dictators all over the world. And God only knows Saddam Hussein was a brutal dictator. We could overthrow Assad tomorrow if we wanted to. We got rid of Qaddafi. But the point about foreign policy is not just to know that you can overthrow a terrible dictator, it's to understand what happens the day after. And in Libya, for example, the United States, Secretary Clinton, as secretary of state, working with some other countries, did get rid of a terrible dictator named Qaddafi. But what happened is a political vacuum developed. ISIS came in, and now occupies significant territory in Libya, and is now prepared, unless we stop them, to have a terrorist foothold. But this is nothing new. This has gone on 50 or 60 years where the United States has been involved in overthrowing governments. Mossadegh back in 1953. Nobody knows who Mossadegh was, democratically elected prime minister of Iran. He was overthrown by British and American interests because he threatened oil interests of the British. And as a result of that, the shah of Iran came in, terrible dictator. The result of that, you had the Iranian Revolution coming in, and that is where we are today. Unintended consequences. So I believe as president I will look very carefully about unintended consequences. I will do everything I can to make certain that the United States and our brave men and women in the military do not get bogged down in perpetual warfare in the Middle East.

Clinton responded first by noting that Sanders has not opposed regime change in every case (which is true, but it doesn't say a lot about Clinton's own judgment). And then she moved on to the argument the Clintonites always raise when Sanders cites her support for the Iraq war: "I do not believe a vote in 2002 is a plan to defeat ISIS in 2016."

That might have been an effective response if Sanders had simply brought up her Iraq vote and left it at that. But of course he hadn't stopped there. He had put her vote from 2002 in the context of her career-spanning support for an aggressive U.S. foreign policy, reaching up to her recent tenure as secretary of state; and he had put that, in turn, in the larger context of a series of Washington-sponsored regime changes that began before the public had heard of Hillary Clinton. He made a sustained argument both that Clinton's approach to foreign policy is fundamentally wrong and that it is part of a long tradition of destructive intervention around the globe. And he was essentially right.

The second high point came shortly afterward. After Clinton gave a brief spiel about the decision to send Navy SEALs against Osama bin Laden, Sanders steered the discussion toward something his opponent had said the last time they butted heads onstage:

[I]n this last debate, she talked about getting the approval or the support or the mentoring of Henry Kissinger. 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 that Henry Kissinger is not my friend. I will not take advice from Henry Kissinger. And in fact, Kissinger's actions in Cambodia, when the United States bombed that country, overthrew Prince Sihanouk, created the instability for Pol Pot and the Khmer Rouge to come in, who then butchered some three million innocent people, one of the worst genocides in the history of the world. So count me in as somebody who will not be listening to Henry Kissinger.

Again it was a sharp attack, both in terms of being basically correct and in terms of laying bare some of Clinton's core problems on foreign policy. Not all of the exchange that followed was as illuminating as that—Sanders made an argument about Kissinger, the domino theory, and trade with China that wasn't very coherent. But the key point had been made: Hillary Clinton embraces the praise of a man whose record includes the "secret" bombing of Cambodia, the Christmas bombing of North Vietnam, and the coup that installed Augusto Pinochet in Chile. Bernie Sanders may not be a foreign-policy whiz, but at least he knows better than to seek counsel from that guy.

After the debate, the CNN panel chortled a little over the Kissinger chatter, suggesting that young viewers would have to Google the man to know who the candidates were talking about. And no doubt quite a few of them were in the dark. But then, such voters would have had to Google the guy when Clinton brought him up in the last debate too. If they did, they'd have plenty to think about as they contrasted Sanders' account of Kissinger's career with Clinton's comment that she was "flattered" by the old butcher's praise.