Korea was ruled by Japan from 1910 until the closing days of World War II. In August 1945, the Soviet Union declared war on Japan, and with the agreement of the United States, occupied Korea north of the 38th parallel. At roughly the same time, the United States occupied the south causing a Japanese surrender. Within three years in 1948, two separate governments had emerged with both believing that they were the legitimate government on the peninsula with neither accepting the legitimacy of the other.

On June 25, 1950, North Korean forces supported by both the Soviet Union and China invaded South Korea. The move into the south caused the United Nations to call the move by the north an invasion and called for an immediate ceasefire between the two which was never heeded. As a result, the United Nations dispatched forces to defend South Korea. While twenty-one nations participated in the defense of South Korea, the United States contributed nearly 90% of the forces.

Within a few months of the invasion South Korea was close to defeat until an amphibious landing of UN forces at Inchon changed the tide of the war in September of 1950. The landing effectively cut off tens of thousands of North Korean soldiers who were driven back to the Chinese border at the Yalu river. In October of 1950, Chinese soldiers crossed the same river and entered the war leading to yet another reversal of the tides of war and led to a war of attrition that lasted until 27 July 1953, when an armistice was signed.

What was a Chinese patrol boat doing in South Korea?

According to South Korea’s defense chiefs, the ship which South Korea assumed was a North Korean boat “retreated as the warning shots were being fired.” According to a South Korean Defense Ministry official, the boat was actually a Chinese patrol boat looking for illegal Chinese fishing boats.

Small wooden fishing boats from China often fish in South Korean waters and are generally allowed to go about their business by the South Korean navy stationed there to spot North Korean vessels crossing the Yellow Sea border between North and South.

However, in recent years those small wooden boats have been replaced by large steel trawlers that drop huge nets on the sea floor to meet growing demand for seafood in China. This illegal fishing has left the Seoul government begging the Chinese to step up their enforcement of this maritime poaching. Since 2011, over 2,200 Chinese vessels have been fined for illegal fishing and has also led to an increase in arrests.

Contentious sea “border” is often deadly

The Northern Limit line of the Yellow Sea has been site to a number of naval squabbles turned deadly. In May 1995, North Korean forces fired on a South Korean fishing boat resulting in the deaths of three fishermen. June 1999 saw numerous exchanges of fire between the two nations resulting in a handful of deaths.

In June of 2002, more naval clashes near the line resulted in the deaths of four South Korean sailors as well as the loss of a vessel. The number of North Korean casualties still remains unknown.

The worst incident, or deadliest, occured in May of 2010, when the ROKS Cheonan was sunk near the Northern Limit Line by a North Korean torpedo. While a rescue operation recovered 58 South Korean sailors, 46 were killed in the attack.