By Keith Howard Regional analyst

Almost 50 years ago, in 1953, the Korean War concluded with an armistice agreement.

The two rival states on the Korean peninsula have to this day never signed a peace treaty.

The armistice itself took some 18 months to hammer out after the war had reached a stalemate, and much of the argument concerned the coastal area bordering the ceasefire line to the West - part of the Yellow Sea.

South Korea and North Korea still have not signed a peace treaty.

The adjacent mainland county around the historical city of Kaesong was eventually left in North Korea, but Yeonpyongdo and a line of islands offshore, in a sea swarming with fish and crabs, remained in disputed territory.

North Koreans say that the islands protect Kaesong, but South Koreans know they sit squarely in the channel ships must take to reach the mouth of the Han River - the river that runs through the capital, Seoul.

The South effectively won, establishing a "Northern Limit Line" that left the territory patrolled by the southern navy.

Response tested

Today, South Korean fishermen are still escorted by navy vessels when operating within the area.

North Korean fishermen routinely drop anchor right on the boundary of the area, testing the response.

In June 1999, northern fishermen entered the territory and were pushed back by the southern navy.

Tensions rose when the northern navy arrived, and shots were fired. Within a matter of minutes two northern vessels were destroyed and at least 30 northern troops were killed.

This was marked down as the worst naval engagement between the two sides since the war.

North Korea apologised for a fatal incident in June 2002

Then, the southern navy was already nervous, since two submarines from the North had been discovered in southern waters on the eastern coast a few months earlier.

In those incursions, North Korean "spies" had come ashore, and there had been skirmishes leaving several dozen dead.

In June 2002, another naval clash left five South Korean soldiers dead and an unknown number of casualties on the North Korean side.

North Korean fishermen had entered the disputed territory four times in the previous six months, and the South accused the North of 12 incursions within the last year.

Wake-up call

Political commentators wondered whether the June 2002 incident was part of a ploy to undermine the South Korean president, Kim Dae-jung.

The 1999 incursion came shortly before mid-term National Assembly elections. And presidential elections are due at the end of 2002.

Kim's party, already trailing in the polls, has vested much in its Sunshine Policy - aimed at promoting South-North reconciliation through trade, aid, and family reunions.

In 1999, the policy survived relatively unscathed, and a year later Kim met his northern counterpart for the first ever peacetime summit.

This time? Time will tell, but it may be best to treat each new incident as a wake-up call - a decade after the collapse of the Soviet Union, and with President Bush claiming North Korea as part of an "Axis of Evil", South Korea and North Korea still have not signed a peace treaty.

Keith Howard is a senior lecturer in the School of Oriental and African Studies at the University of London