THIS seems an odd time for South Korea’s leaders to be talking up the prospects of reunification with their country’s evil twin. The economic gap between the rich south and dirt-poor north of the peninsula grows ever wider, implying mounting reabsorption costs for South Korea. And under its latest Kim-despot, the 30-ish, callow but ruthless Kim Jong Un, the North seems as hostile as ever, threatening new nuclear and missile tests and this week conducting live-fire exercises near the disputed maritime border. In response to Barack Obama’s visit to Seoul in late April an official “Peaceful Reunification” committee thundered that the North “must settle its final scores with the US through an all-out nuclear showdown”. And misogynistic bile was spat at the South’s president, Park Geun-hye: a “dirty comfort woman for the US and despicable prostitute selling off the nation”.

Yet Miss Park herself has been enthusing about the benefits of reunifying her country with this surly belligerent. In a press conference in January she picked “lay[ing] the foundation for unification on the Korean peninsula” as a “key task” for her government this year, and described the prospect as an economic “jackpot”. Then, in February, she announced the formation of a committee to prepare for reunification. In March she visited Germany, long watched by South Koreans as a model of national reintegration between thriving capitalists and struggling communists. In a speech in Dresden, where mass protests in 1989 helped topple the old East German regime, she set out three proposals to ease reunification: a “humanitarian” approach to issues such as reunions between millions of divided families; the building of cross-border infrastructure; and a plan to “reintegrate” the estranged peoples of the two countries through increased contact.

The North’s press dismissed this with predictable scorn, calling it the “daydream of a psychopath”. It did indeed seem fanciful for a number of reasons. The prospect that the North would countenance the proposals was negligible. The idea that reunification will bring an economic bonanza is, to put it mildly, controversial. Her colleagues can point to projections that a united Korea would by 2050 have a bigger economy than Japan or Germany. But that is to ignore the monumental short-term costs.

Nor is Miss Park responding to a groundswell of public opinion. Quite the contrary. She and millions of Koreans may dream of reunification but nearly 70 years of division have taken the edge off the pain even of family separation. They have produced two different peoples—one poor, isolated and downtrodden; one well-off, cosmopolitan and free. South Koreans are on average three inches (7.5 cms) taller than Northerners. The lesson of German unification for many in the South was that it was too expensive for them. Younger Southerners seem to be less emotionally attached to the idea of a united Korea. In a poll taken in March only 14% of those in their 20s saw a Northerner as “one of us”.

Nevertheless, the right-wing Miss Park may see political benefits in appealing to those who would traditionally support the opposition and its softer line towards the North, favouring contact, opening up and talk of reunification over sabre-rattling and talk of war. More important, say some of her advisers, is her hope to leave as a legacy a bipartisan approach to reunification, which, she argued in Dresden, is only a matter of time.

The cruel tyranny visited on North Korea by three generations of Kims sometimes seems the exception to Stein’s law, that if something cannot go on for ever, it will stop. At a conference organised by the Asan Institute, a think-tank, in Seoul last month, a room full of North Korea experts was asked for a show of hands on whether Kim Jong Un would still be in power in a year’s time. Almost all thought he would. But plenty of things make his regime look fragile: his youth; his bloody purge last year of his uncle and other rivals; ongoing economic hardship; and North Korea’s increasing access to information from China and the South.

The fear of a political implosion in the North provides the subtext to Miss Park’s proposals. The economic optimism assumes reunification will be peaceful and gradual. An opposition leader, Kim Han-gil, in January applauded Miss Park’s zeal but warned that reabsorption following a “sudden change” in North Korea would be a “catastrophe”. Yet Miss Park knows that is the most likely way it will come about. Talking about reunification is a way of beginning to prepare South Koreans for the day it is no longer an abstract ideal but an unfolding humanitarian disaster.

It is also a way of making her administration look again at its contingency plans for such an event. A big problem, for example, will be what to do with the estimated 1.2m soldiers in North Korea’s army. Mass demobilisation might be dangerous. But South Korea’s armed forces will surely not want to enlist them.

Three into one won’t go

The views of two outside powers have to be taken into account. South Korea’s close ally, America, with nearly 30,000 troops in South Korea, will be concerned above all about securing the North’s weapons of mass destruction. Both South Koreans and Americans concede they have not shared all their planning with the other—still less with China. Yet reunification probably depends on China’s acquiescence. The North as a kind of Chinese protectorate is the alternative to unification. China will not want on its border a united Korea bristling with American ground troops. It may fear that outcome so much that it could try to intervene to install a compliant regime in Pyongyang.

The potential for dangerous misunderstandings is enormous. Yet talks to reduce them between China and South Korea or America seem impossible, so long as North Korea remains a Chinese ally, albeit an exasperating one. It is quite possible to envisage a united Korea, with no American soldiers on its soil yet on good terms with America and with China. It is almost impossible, however, to discern a route from here to there.

Economist.com/blogs/banyan