To stand at Panmunjom - the last border of the cold war - is to feel North Korean hostility.
Armed guards fix their binoculars on visitors on the southern side, even though they might be standing just metres away. Behind them, hidden in the barren mountains, is a military that makes the border between North and South Korea the most fortified in the world.
Much of North Korea's 1.1 million standing army - one of the biggest in the world - is backed by an estimated 4,000 tanks and, dangerously, a complex network of artillery pieces hidden in tunnels kept on a high state of alert just beyond the border. Seoul - one the region's most modern capitals - is less than 100km away.
As the region grapples for a meaningful diplomatic response to North Korea's latest nuclear test on Monday, the military realities on the ground reveal just how important that search is. A military response, even a so-called surgical strike to take out suspected nuclear targets, is considered virtually unthinkable by veteran regional envoys and intelligence analysts. Israeli jet fighters bombed a suspected nuclear facility in Syria in September 2007 - an act that would be far more risky to attempt against a country as prepared as North Korea.
Even, for the sake of argument, if potential hurdles such as winning Chinese and Russian backing for such action were removed, and North Korea's short- and medium-range missiles ignored, Pyongyang has enough conventional weaponry trained on Seoul to make any such move extremely dangerous. There is little doubt it would be perceived by a regime as insular and paranoid as that in Pyongyang as an act of war.
'You only have to look at the border to see that North Korea is not a normal country - the paranoia has bred an extreme military build-up,' one Asian defence attache said. 'There are huge air defences, for starters. And there is no one better at exploiting tunnels and bunkers. Just knowing what they've got and where they've got it - even the basic stuff - is fraught with risk.