SEOUL, SOUTH KOREA - This vast, pulsating city of ten million seems to have doubled in size since my last visit ten years ago.

Dynamic, optimistic, high-tech South Korea is flying at Mach 9: it reminds me of Japan 25 years ago.

The other 24 million Koreans in the northern part of this divided nation are in deep trouble. Many go hungry or subsist on the verge of starvation, victims of the whims of their bizarre Communist monarchy.

In 1950, North Korea, backed by the Soviet Union and, later, China, invaded US-occupied South Korea. Three years of bitter fighting, in which over 2.5 million Korean civilians died, resulted in a stalemate.

An armistice stopped the fighting on the 38th parallel, but the two Koreas and Americans remain on hair trigger alert. A Demilitarized Zone (DMZ) bisects the peninsula: on either side, 750,000 North Korean soldiers face 500,000 South Korean, backed by 37,000 US troops.

Tension on the DMZ is electric. North and South Korea troops glare at one another from fortified positions and observation posts. The world’s thickest minefields and high anti-tank walls extend from coast to coast.

I was warned that even pointing at the North Koreans could trigger a firefight that might lead to full-scale war.

Adding a new dimension of danger, North Korea is estimated to have three plutonium nuclear devices and is developing more bombs using enriched uranium.

It is uncertain if North Korea has managed to miniaturize a nuclear warhead that can be carried on a medium or short-ranged missile. US and South Korean human intelligence about North Korea is amazingly poor. The main source of information on North Korea seems to be diplomatic gossip.

Parts of Seoul, where a quarter of all South Koreans live, lie within range of North Korea’s 170mm guns and 240mm rocket batteries dug into the DMZ’s granite hillsides. North Korea keeps threatening to turn Seoul into “a sea of fire,” and has hinted it might use nuclear weapons against US bases in Japan and Okinawa.

Is North Korea really the dire threat that Washington claims it is? According to South Korea’s right, which is dominated by militant Christian evangelicals linked to their US co-religionists and neocons, the answer is definitely yes. US neocons are particularly concerned that North Korea may supply nuclear weapons, technology or missiles to Israel’s Mideast foes.

However, more moderate Koreans take a less alarmist view of the North. They tend to see the North rattling its cage to get food and fuel from the US, South Korea and Japan. Blood-curdling threats and invective against these nations is North Korea’s favorite sport.

A good example: “death to the South Korean lackey-puppet-running dogs of the US imperialists!” Old Cold Warriors like myself sorely miss such florid Communist invective.

In spite of US warnings about North Korea’s nuclear weapons, many South Korean analysts believe these arms are entirely defensive, designed to deter any possible US nuclear attack. This strategy is working: the US has refrained from military action against North Korea.

If the North fired any nuclear weapons at its neighbors, the waiting US Navy and 7th Air Force would vaporize North Korea (and a part of South Korea as well). The North’s fun-loving leaders are not suicidal. In fact, their imports of prime cognac, Bordeaux wines and cigars are soaring – in spite of an American embargo on luxury goods.

North Korea’s Kim dynasty just wants to be left alone. China, always considered North Korea’s “elder brother” in the Confucian system, is happy to keep the North as a buffer zone for its strategic Manchurian border, and free of US bases. Japan is uneager to see a competitive united Korea. Russia seems indifferent.

South Koreans worry that having to feed and build a liberated North Korea will bankrupt them. Reunification is not inevitable. Some North Koreans may want a separate state under Communist Party and/or military rule, minus the quirky Kims.

Neither side in this six-decade old standoff has any interest in starting a new war. Last week, North Korea agreed to reopen nuclear talks with the US and its neighbors.

But one never really knows what the red-pepper hot Koreans may do next.