In most nations, it would hardly be controversial to use the word “enemy” to describe the country you maintain has just killed 46 of your citizens in cold blood.

But two months after North Korea torpedoed a South Korean warship, Seoul is agonising about whether to use the phrase “arch-enemy” in official policy documents relating to its old foe. The defence ministry says it is still deliberating over whether the epithet – joo jeok – is justified.

The debate makes little practical difference to the crisis but the symbolism and sensitivity are immense because blood ties and fraternal feelings run deep. Although South Koreans have reacted with profound sadness to the deaths of the young sailors on March 26, there are no visceral public displays of rage against Pyongyang. Rather it is deeply problematic for South Koreans to write off the killers, their brothers in the North, as simply the “enemy”.

In his response to the sinking of the warship, Lee Myung-bak, South Korea’s president, did not speak of North Koreans as foreign foes. Instead, he said he was shamed by the behaviour of his compatriots. North Korea, which denies the attack, expressed regret at the deaths of “fellow countrymen”.

This issue is prickly because the human tragedy of the divided peninsula remains raw. Rare but tearful border reunions of families divided by the cold war’s last frontier are powerful reminders of how recently the nation split. Brothers and sisters divided since the 1950-1953 Korean war embrace in tearful reunions, often having been told only days before that siblings long believed dead are alive.

“We South Koreans are used to viewing North Koreans as poor fellow countrymen, or poor brothers and sisters whom we are obliged to help, overlooking wrongdoings. By reviving the term ‘arch-enemy’, South Koreans will think about Kim Jong-il’s regime separately from poor, ordinary North Koreans,” said Choi Choon-heum, a senior research fellow at the Korea Institute for National Unification.

South Korean public opinion can become far more inflamed about incidents involving the US, a close strategic ally, than its smaller and impoverished neighbour. At 24m, North Korea’s population is just under half the size of the South’s. When a US armoured vehicle ran over and killed two schoolgirls in 2002, the deaths triggered huge street protests and attacks against a US base.

It is hard for authorities to counter such anti-American sentiment. In spite of the military’s display of its “smoking gun” evidence of a corroded North Korean torpedo last week, conspiracy theories still abound that a US submarine sank the vessel. Young people and the political left, the most politically active members of Korean society, can be broadly sympathetic towards North Korea , notwithstanding the repressive austere nature of the regime.

Mr Lee showed signs of frustration on Tuesday and suggested it could be time to return to calling North Korea the “arch-enemy”, something which his two liberal predecessors avoided.

He argued that South Koreans had become blind to the “threat lurking right under their noses”. The term “arch-enemy” was introduced only in 1995, when North Korea threatened to turn Seoul into a “sea of fire”.

Michael Breen, a biographer of Mr Kim, said it could be an ideal time for Mr Lee to declare that fraternity was based on globally shared values and democracy and that North Korea, until it conformed with those, really was the “enemy”.

But he doubted that such a definition of brotherhood could be politically palatable in South Korea.

Andrei Lankov, professor at Kookmin university in Seoul, agreed nationalist sentiment would resist such characterisation.

“There is a mythology that Koreans do not kill Koreans,” he said.

He observed that this was the case in both Koreas, with gory murals in North Korea predominantly showing American soldiers butchering North Koreans, rather than South Korean troops doing so.

Additional reporting by Kang Buseong in Seoul

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