If Kim Jong Un thinks he can shake down Washington by threatening nuclear apocalypse, President Obama says, the belligerent North Korean dictator has another think coming.

“Since I came into office, the one thing I was clear about was: We’re not going to reward this provocative behavior,” Obama told NBC’s Savannah Guthrie in an interview last week. “You don’t get to bang your spoon on the table and somehow you get your way.”

No rewards for Pyongyang’s criminal regime or its bloody-minded young tyrant. Everyone clear on that?

Well, maybe not everyone.

Speaking to reporters in Tokyo the day before the president’s TV appearance, Secretary of State John Kerry suggested that the US government would in fact be amenable to rewarding Kim, who has proclaimed a “state of war” with South Korea, vowed to rain missiles on US military bases, and announced that the nuclear reactor at Yongbyon would be restarted. If Pyongyang tones down its missile-rattling and makes “some kind of good faith” commitment to dismantling its nukes, said Kerry, “we’re prepared to reach out” with concessions – including a renewal of diplomatic negotiations.

“I’m not going to be so stuck in the mud that an opportunity to actually get something done is flagrantly wasted because of a kind of predetermined stubbornness,” Kerry intoned. “You have to keep your mind open.”

An open mind can be a fine and enlightened thing. “But privileging one’s open-mindedness over bitter experience is an exercise in wishful thinking,” observes Michael Auslin, an Asia scholar at the American Enterprise Institute and former professor of history at Yale. For decades, North Korea’s dictators have used threats to blackmail their way into negotiations, which invariably end with a one-sided bargain: North Korea walks off with valuable benefits in exchange for empty promises to halt its provocations.

Kerry’s faith in the efficacy of engaging the world’s most barbaric rulers is an old story. As chairman of the Senate Foreign Relations Committee, he was “very, very encouraged” that his diplomatic overtures to Syrian dictator Bashar al-Assad would culminate in reform and warmer US-Syrian ties. And he had little patience for those who warned that returning to the negotiating table with North Korea would only stimulate further brinksmanship. The “best option” was to “launch bilateral talks with North Korea,” Kerry argued at a Senate hearing in 2011. “We must get beyond the political talking point that engaging North Korea is somehow ‘rewarding bad behavior.’ It is not.” (The insistent italics are in Kerry’s text.)

That hearing came not long after Pyongyang had torpedoed a South Korean patrol boat and shelled a South Korean island – unprovoked assaults that left 50 people dead. Kim Jong Il, the father of the present dictator, never paid a serious penalty for those deadly crimes. His son has drawn the logical conclusion.

In fairness, Obama has been more resolute in dealing with North Korea than his two predecessors ever were. In response to Kim Jong Un’s latest series of grisly threats and nuclear bombast, the president at first made a point of dispatching B-2 bombers and F-22 stealth fighters to South Korea.He also moved a Navy missile-defense ship closer to the region.

Yet with Kerry’s trip to Asia, the administration’s firmness began to melt. “We have lowered our rhetoric significantly,” the secretary of state insisted during a press conference in Seoul. He announced that a regularly scheduled US missile test had been cancelled as a sign of American goodwill. “We are attempting to find a way for reasonableness to prevail here, and we are seeking a partner to deal with in a rational and reasonable way.”

Unfortunately, there is no such partner in Pyongyang. There never will be as long as the pathological Kim family regime remains in power. Kim Jong Un, the son and grandson of totalitarian megalomaniacs, presides over a horrific concentration camp of a state in which hundreds of thousands of North Koreans are brutally enslaved and millions have been starved to death, while resources are showered on one of Asia’s largest militaries. Such a gangster is not going to be wheedled or cajoled into dismantling his illicit nuclear weapons, and pleading with him for more “reasonableness” will only convince him that brinksmanship pays. It is exactly the wrong message to send.

The right message is the one Obama voiced on NBC: “We’re not going to reward this provocative behavior.” That should be Washington’s unshakable policy, and the president should insist that his secretary of state not undermine it with talk of concessions or a return to negotiations. Diplomacy won’t make Kim Jong Un less of a threat. A US president who hangs tough against one of the planet’s most savage blackmailers just might.

(Jeff Jacoby is a columnist for The Boston Globe.)