During the years immediately following the armistice of 1953 that ended the Korean War, from time to time someone in Washington would suggest reducing the American forces in Korea, then numbering two divisions. Whenever this happened, Rhee would fall back on one of two more or less set speeches. Very loudly, he'd either claim that this would expose the ROK to a new invasion from the north, or he would start talking about the "liberation" of the north from the communists. The "expose the ROK" approach would play well with America's the more ardent anti-communists, who would then demand that the US garrison in Korea be maintained, or even strengthened. The "liberation" approach was useful with more centrist or liberal political leaders in the US, since it made him sound like a maniac ready to ignite a new war, which made keeping the American contingent in Korea strong one way of restraining him.
The 'Dear Leader' seems to have studied Rhee's methods carefully.
July 16, 2006: North Korea responded to the UN threat of sanctions by threatening a resumption of the Korean War.
July 15, 2006: The UN Security Council voted unanimously to call on North Korea to stop its missile tests and acquisition of missile technology. The UN resolution is words without teeth, but in UN terms, that's major progress. The North Koreans set a new speed record by issuing an official denunciation of the UN resolution less than an hour after the UN issued it.
July 9, 2006: Japan is cutting back on economic aid to North Korea, as are China and South Korea. This will hurt North Korea, which is still living hand-to-mouth, despite a good harvest. What is hurting North Korean militarily are increased restrictions on North Korean use of the world banking system. American sanctions earlier this year made the North Koreans howl, and now Japan is cutting off North Korean access to banking functions.
North Korean leader Kim Jong-il is by no means as "irrational" as he is usually portrayed. He's actually playing to a very old Korean script; threaten extreme actions so that your enemies—or your friends—decide you need calming down, and offer concessions. The previous master of these tactics was Syngman Rhee, President of the Republic of Korea from 1948 to 1960.