The Kaesong Industrial Complex is a big commercial plant located just on the North Korean side of the demilitarized zone, staffed by South and North Koreans. It's a source of cheap labor for the South and hard currency for the North. It's also a sign that Pyongyang, since it was keeping the plant open despite acting as if World War III were imminent, was bluffing about war. Or at least it was until North Korean guards closed the plant late Tuesday night, sending home the South Korean workers and barring their entry back in.

Does this mean that war is now imminent? Well, no. It's still very much in North Korea's interest to avoid war; this move is likely just a provocation. This is also not the first time that North Korea has closed the plant, and previous closures have been brief.

The Post's Chico Harlan, reporting from Seoul, tells the story of Kaesong and its role on the Korean peninsula.

Above is a video, just a week old, from inside the Kaesong complex. It's interesting to see South and North Koreans working side-by-side, the stern-faced guards, the trucks driving goods in and out. Recall that North and South Korea have technically been at war for 60 years now, so setting up a jointly run and staffed facility, where South Koreans drive in every day under the eye of North Korean troops, is no small task. The plant was originally meant to be a symbol of new cooperation and harmony between the two countries, and you can still see the legacy of that intention here. But you can also see what it's become: an island of cash-driven cooperation amid a much more tense and difficult relationship.

In November, economist and North Korea expert Stephen Haggard estimated that the complex had earned North Korea $61.76 million in hard currency in 2011 and $45.93 million in just the first half of 2012.

Below, you can also see a video taken Wednesday morning local time of the cars streaming out of the now-closed facility: