Expectations are running high that North Korea will do something provocative in the next few days to mark the biggest day of the year on the North Korean calendar.

April 15 is officially known in North Korea as "The Day of the Sun" and marks the birthday of the founder of North Korea, Kim Il-sung, in 1912. It's called that because il-Sung means "to realise the sun" in Korean – although this is not the founder's real name, it's his nom de guerre.

Kim Il-sung was an anti-Japanese guerrilla during the first half of the 20th century, when Korea was one country and occupied by the Japanese. At the end of World War II, the peninsula was divided along the 38th parallel, with the Soviet Union overseeing the northern half and the United States taking the southern half.

Stalin installed Kim Il-sung as the leader of North Korea - but he was not the Soviet Union's first choice. That was a political leader known as "Korea's Gandhi" but he was not a Communist and did not want the job. So they turned to Kim, who had a reputation in Korea as a heroic fighter in Manchuria against the Japanese.