North Koreans are famous for belligerent rhetoric. Most recently, they’ve threatened to turn Seoul into a “sea of fire.” The North’s new leader, Kim Jong-un, comes across as a madman strutting around in a 1950s cartoon. Such flamboyance can tempt people to dismiss the North Koreans as either a joke or too crazy to be taken seriously. This is a mistake. They are not crazy, but wily operators who know how to play brinkmanship to their advantage.

Over the years, the North Koreans have learned that outrageously provocative behavior is never punished. In 1968, North Koreans seized and tortured the crew of the USS Pueblo, releasing them only after the United States apologized for spying. In 1976, they hacked to death two U.S. soldiers trying to cut down a tree in the joint security area at Panmunjom. In response, President Ford sent in a force — strangely called Operation Paul Bunyan — not to retaliate, but to surround and cut down the offending tree. As recently as 2010, North Korea shelled a South Korean island and sank one of its ships; except for some limited South Korean return fire, the best the world could muster were a lot of heated words.

The North Koreans, naturally, have drawn two lessons: First, that South Korea and the United States will do practically anything to avoid a conflict. Any action short of an all-out invasion of the South is likely to be met only with a lot of heavy diplomatic breathing. Second, that international isolation actually pays. It leads the United States and South Korea not only to constantly solicit diplomatic talks, but even occasionally to give Pyongyang aid if it only promises to stop its threatening behavior.

Two cases making this point were the Agreed Framework and the six-party talks. Despite U.S. fuel aid to North Korea, Pyongyang violated the Clinton administration’s Agreed Framework by covertly enriching uranium for nuclear weapons. Initially, George W. Bush took a tough line against Pyongyang. By the middle of his first term, though, Mr. Bush helped launch the six-party talks. Like the Agreed Framework earlier, all the talks did was give North Korea more time to perfect its nuclear and missile programs.

As Heritage senior fellow Bruce Klingner says, “North Korea provocations are usually initiated when they have the greatest potential to garner attention and advantage, raise sufficient concerns of escalation to force opponents to not respond, contain the crisis and seek resolution, and enable Pyongyang to deny or deflect responsibility.”

This appears to be the game plan today. Over the past few weeks, North Korea has ratcheted up the rhetoric. It declared the armistice ending the Korean War null and void and even threatened the United States with nuclear war. It’s not unusual for Pyongyang to uncork the rhetorical bottle when the United States and South Korea undertake joint military exercises, but this time seems to be more serious.

Two things appear to be going on: First, the young Mr. Kim is trying to prove himself, not only to us, but possibly to his own people, by playing tough. Second, and more worrisome, the leadership may be emboldened by the belief that they’re very close to possessing a nuclear missile capable of reaching the United States.

The situation is ripe for miscalculation. The new South Korean president, Park Geun-hye, whose mother was killed by a North Korean agent, has made it clear she will not roll over like other South Korean leaders. Moreover, there is a new U.S.-South Korean agreement that could result in the United States more forcefully backing the South militarily short of all-out war. Another North Korean attack could result in the U.S. forces joining South Korea in some form of military retaliation.

Either way, we should not think this is a case of parties on the peninsula crying wolf. North Korea has shown time and time again it will strike with violence. It may well be on the verge of doing so again.

-Kim R. Holmes, a former assistant secretary of state, is a distinguished fellow at The Heritage Foundation.