Conducting a nuclear weapons test will not mean that North Korea has useable nuclear weapons, but does mean that the government means to replace its increasingly unreliable army, with a few nuclear weapons. This is needed to provide a credible threat to South Korea. You cannot run an extortion racket unless you can make a credible threat.
October 3, 2006: Having nearly run out of threats, North Korea now says it will test a nuclear weapon soon. Everyone in the neighborhood condemned this, and the U.S. threatened an unspecified, but "severe," response to such tests.
October 1, 2006: South Korea is buying $1.5 billion worth of American Patriot anti-aircraft missiles, including some of the anti-missile version. Deliveries will begin in 2008.
September 30, 2006: The U.S. Army is disbanding the 8th Army headquarters, which was first established during World War II, and has controlled American ground forces in South Korea since 1950. This headquarters was also set up to control all UN forces, including South Korean, in time of war. But this is changing by 2008, with South Korea retaining control of its own troops in wartime. So the U.S. is reducing its headquarters troops. The U.S. 2nd Infantry Division is taking control of all American ground forces.
North Korea is facing a real disaster, and it has nothing to do with nuclear weapons. Famine is back, with the prospect of hundreds of thousands of famine deaths over the Winter. North Korea has put more restrictions on the monitoring of foreign food aid, which has resulted in less food coming in. North Korea says it doesn't care, but for millions of North Koreans on short rations, this is a matter of life and death. It's also a matter of stability. Over a decade of famine and economic upheaval, has shaken the effectiveness of the North Korean police state. Corruption grows year by year, while readiness and discipline in the armed forces declines. The secret police are also on the take, which accounts for the growing number of North Koreans getting out of the country. The corruption has gotten so bad that those who have gotten out, and made some money, can now bribe officials back in North Korea, and get their families out. It appears that everything is for sale in North Korea, although there is less and less to buy.