Korea's DMZ: 'Scariest place on Earth'

The world's tallest flagpole dominates the North Korean side of the frontier

(CNN) -- Former U.S. President Bill Clinton described it as "the scariest place on Earth."

The Demilitarized Zone (DMZ) that divides the two Koreas is the most heavily fortified border in the world, bristling with watchtowers, razor wire, landmines, tank-traps and heavy weaponry.

On either side of its 151-mile (248 km) length almost two million troops face each other off ready to go to war at a moment's notice.

They have been on a hair trigger for almost 50 years, ever since the last shot was fired in the Korean War and an uneasy truce came into force.

Officially that war has not yet ended -- no formal peace deal has ever been signed and the war could start again at any moment.

Between North and South is a strip of rugged no man's land -- the DMZ proper -- averaging two and a half miles (4km) wide.

A sense of tension fills the air -- along with, from time to time, the sounds of martial music and propaganda blasted out from giant speakers installed along the North Korean side.

Also on the North Korean side is what the Guinness Book of Records lists as the world's tallest flagpole soaring some 160 meters (525ft) into the air.

Flashpoint

Almost two million troops are stationed along the heavily-fortified frontier

Monitoring the edgy standoff is a small group of Swiss and Swedish officers who make up the Neutral Nations Supervisory Commission.

For its part North Korea is thought to maintain about one million troops along its side of the frontier.

On the southern side, stationed alongside some 600,000 South Korean soldiers are 37,000 U.S. troops, one of the largest single overseas deployments of American forces.

If North Korean forces ever crossed the DMZ again the United States is automatically at war -- under a 1954 treaty backed by United Nations resolutions the U.S. is committed to defend South Korea.

Although one of the world's major flashpoints, the DMZ has become a major tourist attraction drawing in hundreds of thousands of visitors a year.

Many come to gawp at the rigid North Korean soldiers stationed along the frontline.

Others take in visits to one of a number of tunnels dug secretly under the DMZ by the North for use in a possible invasion.

Virtually undisturbed for half a century the zone has also become a rugged natural haven for several endangered species including the white-naped and red-crowned cranes as well as nearly extinct Korean subspecies of tiger and leopard.