The Cheonan sank in a contested sea area on the western side of the Korean peninsula. Several naval skirmishes have been fought there during the past twelve years. In November 2009, a seriously damaged North Korean warship had to retreat home after a clash.

“South Korean newspapers have quoted intelligence sources that say that the sinking of the Cheonan is a revenge for that incident. As far as we know, it is likely partial explanation,” says John Rydqvist, security policy analyst at FOI. “The severity of the ‘revenge’ is due to North Korea being more under pressure today than three-four years ago. During the early 00s, liberal South Korean politicians pursued a friendlier line towards North Korea, something that Pyongyang benefited from and exploited. The 2008 elections brought a conservative government into power in Seoul, shifting to a more sceptic attitude to the neighbour. The relations between the states became colder.”

North Korea has a history of behaving provocatively followed by switching to a more reasonable posture to make political gains. For instance, the tests of nuclear devices and missiles during recent years have been used for that purpose. “But Pyongyang’s strict denial of involvement in the Cheonan incident and its claim that all evidence are fabricated do not follow the usual pattern, which indicates another underlying cause,” says John Rydqvist.

However, the opportunities to study North Korean decision-making are limited, because almost no first-hand information about the rulers is released. Analysts are limited to interpreting official statements by the KCNA news agency and the overt actions of the state. Sometimes additional information can be derived for North Korean diplomats.

“Government representatives in Seoul have commented on the report of the investigating committee in different manners. Threatening words that Pyongyang will have to face consequences for its actions have been mixed with statements that any reaction must be measured and not hasty. Seoul has implemented new economic sanctions and intends to go, together with the United States, to the UN for international sanctions. They want to prevent escalation while putting pressure on the Kim Jong-il government to change its policies. But Pyongyang has so far proven its skill in evading such moves,” says John Rydqvist.

It is very unlikely that the conflict will cause a full-scale war. The North Korean army is huge but antiquated and Pyongyang knows that it cannot win on the battlefield. On the other hand, the government in Seoul knows what devastation North Korean artillery would cause in the capital in the first day of a war.

“When it comes to Seoul’s intention to bring the matter to the UN Security Council, China will have to take sides,” says John Rydqvist. “Beijing can keep on protecting its unruly ally or make a serious gesture against it. But in reality, China has little choice. The survival of its ruling party is at the top of the agenda, making domestic policies top priority. If North Korea would collapse, the flood of refugees going north across the Yalu river would affect that poor region of China badly. And if China continues its economic support of North Korea, the effects of UN sanctions would be limited.”