North Korea seeks attention through show of power
Nobody needed any reminder of the volatility of relations between North and South Korea nor of the sensitivity of this zone close to the disputed maritime border between the two countries.
Last March a South Korean warship was sunk by an explosion - with the loss of 46 lives - and an international investigation indicated strongly that the North Koreans were responsible.
Now, the shelling of this small South Korean island fits into the same pattern.
From the North Korean viewpoint this is about establishing a deterrence strategy over the South and defending its vital interests.
An annual South Korean military exercise is under way across the country. The North Koreans demanded that this be halted. And when it went ahead, for whatever reason, this clash erupted.
However, this episode is much more than just an opportunity for the regime in Pyongyang to rattle sabres, bolster the morale of its own population and dismay that of the South.
It represents a demonstration to the outside world of North Korea's power and - many analysts believe too - that it is symptomatic of some kind of political transition at the very top of the North Korean power structure.
Quite what is going on in the North Korean capital, Pyongyang, is very hard to say; the inner workings of North Korea's government are almost impossible to discern from outside.
Nonetheless there are strong indications that Kim Jong-il - North Korea's ailing ruler - has designated his son, Kim Jong-un, as his likely successor.
How this is going down within the regime's ruling circles is unclear. Is there jockeying for influence? What does the military think? Are factional struggles bubbling to the surface? Nobody outside the country really knows.
Inevitably this all opens up a period of uncertainty and unpredictability and just this kind of military incident is exactly what some seasoned Korea observers most feared.International condemnation
Demonstrating its military power and resolve - just like the recent revelation of a massive uranium enrichment facility in Yongbyon - also serves Pyongyang's wider diplomacy.
It wants to get the attention of the outside world - notably the Americans. Some argue that Pyongyang is eager to return to talks about its nuclear capability, albeit at a price.
The problem is that decoding Pyongyang's intentions from its actions is never easy. And this - linked also to the fact that there are very few levers that can be pulled to influence this isolated country - is what makes devising a strategy to cope with this incident so difficult.
Diplomatic reaction has been swift, with China expressing its dismay at the turn of events without specifically condemning the North.
Russia has been more emphatic in blaming the North Koreans while both governments insist on the need for a diplomatic solution to the problems between the two Koreas. China in particular wants the suspended six-party negotiations on North Korea's nuclear programme to be resumed without delay.
Not surprisingly, Western governments have taken a tough stance towards Pyongyang; with the White House spokesman calling on North Korea "to halt its belligerent action".
The US, he said, is "firmly committed to South Korea's defence". The British foreign secretary, William Hague, also condemned what he termed "an unprovoked attack" on this South Korean island.Military danger
The problem is what to do next? For the US and its South Korean ally military escalation has to be avoided.
For all the talk about the balance of military power on the Korean Peninsula two things are clear. In all probability the US and the South Koreans would eventually win any all-out conflict. But at what cost ?
The South Korean capital, Seoul, is relatively close to the border with the North - well within artillery range of probably thousands of guns. It would be devastated in any war and the casualties would be appalling.
In a strange way Washington's military strength almost deters the South from taking any significant military action for fear of the North just moving up the ladder of escalation risking an all-out crisis.
Well-telegraphed steps may be taken to demonstrate US military resolve but the real focus is going to be on diplomacy.
But here Washington and Beijing are at loggerheads; the US insisting in the wake of the revelations about North Korea's new uranium enrichment facility that there can be no question of resuming the six party talks now.
The shelling may well go to the United Nations Security Council in New York and there China's position will be closely watched as an indication of the level of its frustration with Pyongyang.
Managing this crisis is all very well in the short-term, but with North Korea back at the top of the international agenda, the pressure is going to be on the Obama administration to re-think its current approach.
The political uncertainty in Pyongyang makes the diplomatic track even more difficult. But in its absence there is always the stark danger of military action from the North escalating out of control.