But more than 57 years after the armistice suspended open hostilities between the U.S.-allied Republic of Korea in the south and the Chinese-backed Democratic People's Republic in the north, their border remains trip-wire tense. And both sides are braced for a return to conflict, however unlikely, that would kill millions of people and resonate economically and politically across the globe.
In the South Korean capital of Seoul today, residents participated in a 20-minute air attack drill by donning gas masks and rushing into underground shelters. It was the biggest evacuation exercise in decades and one treated with an unusual seriousness in the wake of last month's artillery clash.
North Korea's rhetoric has become exaggeratingly bellicose -- a standard practice for Pyongyang -- with the state-run Korean Central News Agency most recently saying joint U.S.-South Korean military exercises in the Yellow Sea brought "the dark clouds of a nuclear war to hang over the Korean peninsula."
And these days, the international community isn't dismissing the threat.
An apparently evolving transfer of power in North Korea, along with the country's perpetual economic frailty and extreme paranoia, has put the U.S. and South Korea on edge and scrambling for ways to calm the situation.
"It's changed out there, and it's dangerous. Increasingly dangerous," Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, told troops in Baghdad this week when asked about the Korean standoff.
In addition to what's thought to be a rudimentary nuclear arsenal of perhaps a dozen bombs, the North Koreans have a million-man army, with half deployed near the demilitarized zone abutting South Korea, and hundreds of long-range artillery tubes within range of Seoul. That means a sudden strike could potentially kill the roughly 30,000 American civilians living among the millions of South Koreans, as well as the roughly 25,000 U.S. servicemen and women assigned to protect South Korea.
In turn, U.S. and South Korean firepower can destroy the North Korean leadership and military.
"North and South Korea have never been closer to war since 1953, but close is actually not too close because of the terrible consequences of war for both sides," as the national security veteran analyst Leslie Gelb put it recently.
Still, unpredictability is one of North Korea's most dominant characteristics, and the fields of potentially deadly miscommunication or misinterpretation are many.
After the sinking of the Cheonan in March and South Korea's angry accusations against the North, Pyongyang shut down a military-to-military hot line that had been set up in 2004 for the two sides to handle maritime emergencies.
It also periodically turns off the United Nations fax machine link at Panmunjon, along the DMZ, like a small child acting out.
North Korea's own insular and despotic regime -- built around a cult of personality toward leader Kim Jong Il -- could get in the way of understanding any external threat and internal weaknesses.
After Saddam Hussein was deposed, plenty of evidence emerged that he didn't know the limits of Iraq's defenses because frightened subordinates were afraid to tell him.
"Pyongyang's grasp of potentially fast-moving events could be quite limited and slow, given the North's relatively unsophisticated intelligence and communication systems," Stares said. "Furthermore, the limited options for communicating with the North Korean leadership could hinder attempts to bring a rapidly deteriorating situation under control."
Equally destabilizing is the North's current, apparently volatile succession process.
The ailing Kim Jong Il has tapped his third son, the young and inexperienced Kim Jong Un, to be the next leader, as evidenced by the younger Kim's recent promotion to four-star general and what appears to be the establishment of Kim family members and allies in a de facto ruling council that will advise him.
Kim Jong Un may be behind the recent and possibly future acts of aggression as a way of establishing his credibility with the military, just as his father was believed to have done when -- after a playboy-like youth -- he was preparing to succeed his father, North Korean founder Kim Il Sung.
But North Korean politics are extremely hard to decipher from afar, and it's possible that factions within the government or military could oppose Kim Jong Un, creating the potential for even more volatility.
Pyongyang also has a history of using aggression to get the world's attention in order to get food, fuel or other aid through negotiations. And though it has mastered the art of brinkmanship, the North always runs the risk of overplaying its hand.
Operations Plan 5027
The North Koreans do know there is no way they could come out ahead in full-out war, but they also know they could inflict a tremendous amount of damage before the U.S. and South Korea could stop them.
In some ways, the thrust of each side's military threat is the unbearable cost to either of a first strike. If North Korea attacks the South with the decades-old motive of forcing reunification, U.S. and South Korean air and sea power can obliterate all key military targets, invade and topple the regime. In the unlikely event of the South and U.S. forces instigating a conflict, the North can destroy Seoul, send missiles toward Japan and attack with a missile or airplane-carried nuclear device.
The U.S. military perpetually updates its contingency plans for war in Korea, a document known as Operations Plan 5027, or simply OPLAN 5027.
It officially envisions the U.S. providing units to reinforce South Korean in the event of an attack, but the commander of joint forces would be an American.
As parsed by the security documentation compiler GlobalSecurity.org, OPLAN 5027 lays out some scary possibilities.
The roughly 500 artillery tubes trained on Seoul, twice the firepower the North had in the 1990s, could devastate the South's capital. They are part of a 12,000-strong force of self-propelled and easily moved artillery and rockets. And though they are old, they could sustain a firing pace of up to 500,000 rounds per hour against the U.S.-South Korean Combined Forces Command defenses for several hours.
The private political intelligence group Stratfor notes that the shells used in the recent attack on Yeonpyeong Island were incendiary and possibly thermobaric -- a class of so-called fuel-air bombs that produces much longer blast waves than traditional explosives with the aim of increasing casualties and property damage.
In analyzing the pattern of fire and results, Stratfor adds that there was a fairly high dud rate -- roughly a quarter of the rounds that failed to explode.
Fire and Flood
But the North still has the power to destroy a half-century of industrial development in South Korea, a country that's a key trading partner of the U.S. and an integrated cog in the global economy. That's in addition to the devastation it could cause to the South Korean population and its American and other foreign guests.
North Korea also has the manpower to stage a short-term blitzkrieg of the South with little time needed for preparation, though the U.S. and South Korean air superiority would likely stop that advance from going all the way to Seoul.
And the North could unleash chemical and biological weapons, its small nuclear arsenal, and even flash floods with dams upstream from the DMZ.
The U.S. counteroffensive plans are all about stopping the North Koreans in their tracks and quickly decapitating the regime.
As the North Korean forces work their way through the rugged, mountainous terrain to the south, U.S. air power would use the northern tanks and infantry's narrow access routes as killing zones.
Meanwhile, as air- and sea-based missiles took out North Korean command and intelligence targets, a U.S. Marine expeditionary force and South Korean units could stage an amphibious assault positioning them to quickly move toward and seize control of Pyongyang.
But the South Koreans would have to withstand days of destruction while such an invasion was carried out.
It isn't clear how North Korea could or would deploy its small nuclear arsenal.
Almost certain is that suspected North Korean nuclear facilities would be among the first U.S. targets.
And almost just as certain is that the U.S. wouldn't retaliate itself with nuclear weapons -- in part because of how that would affect China, South Korea and North Korean civilians, and in part because the U.S. has devastating conventional weapons at its disposal for a Korean conflict.
Still, North Korea's atomic weapons remain one of the biggest question marks on the peninsula. Adding to the confusion, senior Obama administration and intelligence officials told The New York Times that Pyongyang's recently unveiled uranium-enrichment program may be "significantly more advanced" than Iran's, involving hidden nuclear facilities around the country that outsiders haven't detected.
That's sure to be on the agenda of Deputy Secretary of State Jim Steinberg, who left Washington on Tuesday to lead a high-level delegation to Beijing.
As in peace, China would be an extremely influential player on the Korean Peninsula should war break out.
Half a century ago, it fought on North Korea's side. Now, Beijing's affairs seem far too interwoven with the West's to even consider taking sides in such a conflict.
But in war, all bets are off.