Letter from Korea: The razor wire, trenches and skull and cross bone warning signs are the first indications that we are nearing the North Korea border. Pressing hard against the bus window, I can just make out the tell-tale signs of camouflaged military fortifications on either side of the road.
It reminds me of the bad old days when I used to play the "spot a soldier" game with my sister when passing through the border posts between Northern Ireland and the Republic during the Troubles. But the huge scale of the military build-up along the 241 kilometre "demilitarised zone" (DMZ) dividing South and North Korea dwarfs any fortifications seen along the Irish border.
"This is the longest barbed wire fence dividing any nation in the world," says our South Korean guide, who brings thousands of tourists here every year and jokes that she hasn't lost any yet. But her light-hearted banter doesn't prevent us exchanging a few anxious glances when she warns us not to wander into the surrounding mine fields or against defecting across the wire.
Divided along the 38th parallel in 1953 when a military truce was signed between the US, Chinese and North Korean forces, Korea remains one of the few relics of the Cold War. Technically the two Korea's are still at war, and with North Korea's 1.7 million strong army amassed along the border, it is no wonder that tensions regularly run high on the peninsula, often prompting incidents that threaten to draw the US or China into a new crisis.
One of our party, a former US soldier who served at the DMZ for several years in the 1990s, explains how his base would endure several days of "lock-downs" when North Korea amassed troops along the border during its regular manoeuvres.
"There were times of real concern especially toward the end of Kim Il-Sung's reign," he says. "I think they could have overran us and reached Seoul in less than a day had they attacked."
Computer simulations undertaken by the South Korean Institute for Defence Analysis predict the North could take 16 days to overrun Seoul. But this is cold comfort for the capital's residents, as experts predict that a third of Seoul would be reduced to rubble by the North's long range artillery in an hour. And this is not considering its nuclear programme.
About 50 minutes drive from Seoul, we prepare to take a first look into the world's most reclusive State.
We pass slowly through a checkpoint manned by both South Korean and US troops as we make our way to the Dora Observatory, a viewing point that offers stunning views of the DMZ and Gaesong, the second biggest city in North Korea.
I am struck by an eerie stillness that dominates the landscape on the northern side of the four-kilometre wide DMZ. There is no smoke belching from the distant factories and the only thing moving is a car meandering its way towards the border.
"Where are all the trees?" asks one of our tour party.
True enough, on the South Korean side of the DMZ, trees and bushes dot the horizon while hardly a bush is visible in the North. The landscape is a barren wasteland, a moonscape that contrasts sharply with the foliage in the DMZ that has benefited from 50 years of no interference.
According to UNICEF, tree bark became part of the diet in North Korea during a savage two-year famine in the late 1990s. It estimates that 42 per cent of children under the age of seven suffer from chronic malnutrition and some 70,000 children face the danger of death, without prompt and proper medical care.
For South Koreans the situation in the North garners a range of emotions, from fear of attack, to concern for the millions of relatives that remain largely uncontactable 50 years after the division of the peninsula.
But just visible from our viewing point, there is a glimmer of hope on the horizon, in the shape of the Gaesong Industrial Park. The park marks the first big economic joint venture between the two feuding States.
Backed by a private company Hyundai Asan, and South Korean State-owned Korea Land, it is hoped the park will offer jobs to 730,000 North Koreans, who each will earn $50 per month.
More than 10 South Korean firms have already set up factories and hope to benefit from the low cost of doing business in North Korea. A further 130 South Korean firms have joined a waiting list to invest here, which will help bridge the economic gap between the Koreas and help a future reunification.
Our last stop on the tour of the DMZ is at a brand new railway station built close to the border. We all get out again and get our passports stamped on the North Korean border. Perhaps the next time I visit, this reclusive nation will be open for business.