PANMUNJOM, North Korea — Most roads in rural North Korea are little more than dirt tracks, unpaved and constantly maintained by workers shoveling earth to fill ruts and holes.
Not this one.
Just south of Pyongyang, the paved highway suddenly grows to the width of an airport runway — which is exactly what the road is intended to be.
As the borderline of this secretive and highly militarized state approaches, it is clear the deep tunnels and four wide stretches of perfect road surface serve a dual purpose.
Just as rulers have built roads wide enough for marching armies since Roman times, so the road towards South Korea is made for warplanes and tanks.
If arriving in North Korea is like stepping back to the 1970s, then coming to the border is stepping back to 1953.
It is frozen in time to reflect the front lines and power balance at the end of the three-year Korean War, a conflict paused at this spot by the signing of the armistice.
But it's just that — a cease-fire, not a peace treaty, and even that took 718 rounds of talks here, according one North Korean border officer.
And although the border is called the Demilitarized Zone (DMZ), in fact nothing could be further from the truth.
North Korean officials gave NBC News rare access to the DMZ where a two-and-a-half mile strip of land separates the two Koreas and a line of raised concrete no more than three inches wide marks the demarcation line across which no one from either side must take a step.
Blue and silver huts straddle the frontier, their interiors similarly divided: blue for the U.S. and South Koreans, silver for the North.
Security cameras are trained on every yard of land here, though that didn't stop a North Korean soldier defecting across the DMZ to the South last week, according to South Korea.
And while border guards make up the only troops in the no-man's land, the area bristles with weapons and menace for miles around.
On the approach to the zone there are tank traps, mine fields and columns of stone ready to be toppled onto the highway to block invading armies.
And tensions here are higher than they have been for decades.
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North Korea believes the U.S. and its South Korean allies want to invade the country and kill its leader Kim Jong Un, and that a recent joint exercise involving tens of thousands of allied troops practiced that precise objective.
North Korea has carried out two nuclear tests this year, as well as more than 20 missile launches and is determined to strengthen its nuclear weapons program.
So this border isn't just a relic — it is the front line of an unfinished war, and the possible flash point of a newer conflict over nuclear arms.
The North Koreans have their neighbor's capital Seoul in their sights, just 50 miles to the South. They say the Americans have an invasion plan that's targeted at their capital, Pyongyang.
There, just 96 miles from the border on the 38th parallel, Kim Jong Un sits, weighing up the threat from his enemies and the risk of defying the world to counter it.
This is not the friendly frontier — it's a place of accusation and threat, the crucible of Korea's conflict and a potential powder keg of future disputes.