ATLANTA — North Korea recently threatened to “mercilessly destroy” its foes. That didn’t elicit much reaction abroad. After all, the terms were similar to threats uttered countless times during and since the 1950-53 Korean War.

“Pundits describing the North Korean threat often downplay it because it appears obvious that North Korea’s military — despite its large size — is unlikely to be able to unify the peninsula,” said Bruce Bechtol, professor of international relations at the Marine Corps Command and Staff College and an expert on the North Korean military.

This time, though, the regime added that it might employ its nuclear weapons in the process. And there are other reasons, including a newly reported change in the North’s war plans, why outsiders should not assume that the blowhard Kim Jong Il and his generals are all bluff.

“Those who downplay the evolving North Korean military threat do so not at their own peril but that of the Republic of [South] Korea,” Bechtel said in an email. The Northerners “have adapted their military — and their military planning — to changing times.”

Author of the excellent "Red Rogue: The Persistent Challenge of North Korea," Bechtel was commenting on a Tuesday article in the Seoul daily JoongAng Ilbo. The paper quoted an unnamed high-ranking military source in South Korea as saying the North had relinquished its old plan, in case war should occur, of occupying all of the South within a week.

The North’s new war plan, JoongAng Ilbo said, is to quickly grab control of Seoul and the surrounding area just across the border from the North and then decide whether to proceed farther south — or simply stop and negotiate a cease-fire. In the latter case — holding hostage the most populous and developed Korean region by far, the capital and nerve center of the South — the North would have enormous bargaining power with the South and its U.S. ally.

According to Bechtel, “the North Koreans don’t need to unify the peninsula. They just need to take Seoul. Once they take Seoul, they have the overwhelming advantage.” Indeed, with their missiles, special operations forces and maneuver forces “poised on the invasion corridors,” he said, the Northern forces “are built and trained to do just that. For years I have been saying this. Now it comes out in the open press — and this is important — that that is exactly what their war plan is.”

The JoongAng Ilbo article quotes its unnamed source as speculating that the North changed its war plan “to better deal with the upgraded weapons systems of the U.S. and South Korean forces.”

And it quotes an unnamed military expert as explaining that the 2003 Iraq War convinced the North Koreans they would lose if they tried to slog it out over time using their outdated mechanized forces against U.S. weapons systems equipped for precision targeting. The new plan, it says, has added light infantry divisions at the front line to increase the speed with which the North could achieve a fait accompli by taking Seoul.

The JoongAng Ilbo article noted that South Korean military officials think North Korea has acquired late-model torpedoes from Iran, in exchange for submarines, and plans to use them to prevent a U.S.-South Korean landing behind the front lines.

Reports increasingly point to a North Korean torpedo as the cause of a mysterious recent explosion that sank a South Korean warship. With defector reports saying the North has trained zealous military men to pilot manned torpedoes in suicide runs, comparisons to imperial Japan are tempting.

For Americans with tens of thousands of troops stationed in South Korea and a commitment to defend the South against renewed attack, 1941 Japan is a troubling precedent of an enemy that by most objective analysis lacked the power to take on the United States but attacked anyhow and hoped to prevail thanks to guile and guts. (The Confederacy with its attack on the union’s Fort Sumter is another such precedent.)

The comparisons to wartime Japan have also received a boost from the recent publication by North Korea propaganda expert B.R. Myers of a fascinating book "The Cleanest Race: How North Koreans See Themselves and Why It Matters."

“The assumption prevails that the worst Pyongyang would ever do is sell nuclear material or expertise to more dangerous forces in the Middle East,” Myers writes. “All the while the military-first regime has been invoking kamikaze slogans last used by imperial Japan in the Pacific War.”