Day eighteen thousand, give or take a few, of the cease-fire between South and North Korea begins like most other days: Soldiers are preparing for war. In the bitter cold of pre-dawn darkness, 15 South Korean infantrymen huddle together on a road outside a sleeping farm village and streak their faces with camouflage paint. They snap magazines of live ammunition into their M4 assault rifles. With the wind comes a faint strain of martial music, as if from a ghostly parade, carrying from huge speakers mounted across the border in North Korea. At a hand signal from the platoon leader, the soldiers noiselessly line up and then disperse, melting into the surrounding blackness.
Their mission is to patrol a short stretch of the Demilitarized Zone (DMZ), the contentious no-man's-land that has divided the two Koreas for 50 years. The bright lights of Seoul, the South Korean capital, burn less than 35 miles (56 kilometers) away, but here in the fenced-off, land-mined, guard-towered DMZ, the only reality is a shadowy cat-and-mouse game played between soldiers of warring armies. Every 15 minutes the radioman murmurs the platoon's position back to the command post: a road, a rice field dike, now the border itself.
As the platoon approaches a North Korean guard tower, the leader signals his men to stay alert. If the patrol is particularly lucky, a North Korean soldier will recklessly dash through the brush and offer to defect with state secrets. If it is particularly unlucky, the North Koreans will open fire. That would be unlucky for all of us: In a worst-case scenario, Korea's uneasy peace could shatter, spilling war across the peninsula, with millions killed, and then possibly on to China, Japan, and beyond, pushing the world toward possible nuclear war.
Apocalyptic thoughts come easy here. In a world full of scary places—Kashmir, Chechnya, the West Bank—the DMZ is perhaps the scariest of all, considering the massive fire-power deployed on both sides and the brinkmanship practiced by the rival camps. All along the 148-mile (238-kilometer) truce line that bisects the Korean peninsula, hundreds of thousands of well-trained troops from two of the world's largest armies (plus more than half of the 37,000 United States troops stationed in South Korea) stand ready to fight, trained by their commanders to hate their ideological opposites and never to let their defenses down.
This state of emergency has persisted since July 27, 1953, when an armistice agreement halted the vicious fighting of the three-year-old Korean War. The origins of the conflict go back to the end of World War II, when the peninsula was split at the 38th parallel by the Soviet Union and the United States as the Allies drove Japan out of Korea. With the tacit consent of its Soviet patron, North Korea launched a surprise, tank-led invasion across the line on June 25, 1950, seeking to impose communist rule throughout the peninsula. China, another freshly minted communist power, entered the war in October, sending waves of soldiers into North Korea when UN forces threatened to overrun the Yalu River on the Chinese border. By 1953 almost 900,000 soldiers had died—and more than two million civilians had been killed or wounded—as the South Korean military, joined by United Nations troops composed mostly of American units, battled the forces of North Korea and China to a standstill.
The end of fighting did not bring an end to hostilities. To separate enemies straining at their leashes, the armistice carved out the DMZ, a 2.5-mile (4-kilometer) wide swath of mostly mountainous land stretching across the peninsula near the 38th parallel designed to serve as a buffer zone, off-limits to large troop concentrations and to heavy weaponry like tanks and artillery. Straight down its center was drawn the political border, called the Military Demarcation Line (MDL). Then as now, anyone trying to cross the MDL would likely be shot.
To this day, South Korea and North Korea do not recognize each other as sovereign nations. In fact the two Koreas are officially still at war. And often they act like it, keeping tensions sharp as a blade throughout the peninsula and especially along the DMZ.