South Korean officials like to talk of the 'destiny' that the two Koreas will one day unite again. But for an idea of the complexities underpinning that vision, travel by road just over an hour north of Seoul to the demilitarised zone that separates them. It is a trip that will take you from the world's most wired capital to the world's most fortified border - known as the DMZ. It is a place where cold war paranoia still thrives and thousands of artillery pieces are aimed in Seoul's direction. Beyond the barbed wire, the fences and the minefields, you can peer into the world's most isolated state, and one of its poorest. The differences are represented in the geography, too. Forested hills on the South Korean side give way to a treeless landscape in the North that shimmers russet-red under a brittle winter light. Through high-powered binoculars at the Dorasan observation post, you see North Korean guards padding along dusty trails next to lookout huts. No civilians can be seen and the so-called propaganda village - an area of large, free-standing houses from where loudspeakers boom martial music and vitriol into the South - appears abandoned. At first glance the homes look substantial, but they are unpainted and some have bricked-up windows. Beyond are the more substantial buildings of the Kaesong Industrial Park, where North Korean workers toil in South Korean-funded factories, an experiment that persists despite the worsening tensions. Pyongyang and Washington may have started talks about exchanging food aid for a moratorium on uranium enrichment and other military provocations, but on the day we visit last week the joint security area - where rival soldiers eyeball each other just metres apart next to their truce meeting room - was closed to outsiders. Tensions over joint South Korea-US exercises - and fierce Pyongyang rhetoric - made it apparently too sensitive. This week it remains shut, too. North Korea is staging live-fire drills further down the DMZ near the island of Yeonpyeong, where four South Koreans were killed in an artillery barrage in November 2010. Instead, tourists - some of the more than a million that now visit the DMZ each year - flock to the Dorasan railway station and other sites. Pristine, the station, opened in 2002, stands as a monument to dashed hopes, its tracks north blocked. For all the regional diplomacy and long-term desires, in their private moments Seoul officials talk of a fact that is as stark as the landscape. 'Our fundamental objective must be peaceful unification,' one senior official, involved with relations with Pyongyang, said. 'A war on the Korean peninsula would be so devastating that South Korea would never be able to rebuild itself.'