On 12 December 2012 the North Koreans successfully launched a satellite in defiance of U.N. Security Council orders. The launch demonstrated not merely that North Korea could orbit a satellite but, more important, that it now has at least a primitive intercontinental ballistic missile (ICBM).
More than 50 years ago, the immediate military significance of the Soviet Union’s Sputnik, the world’s first artificial satellite, was that its launch demonstrated the Russians actually possessed the ICBM they had announced a few months earlier (the launch rocket was the ICBM). The North Korean test employed a three-stage rocket. In April a similar test failed when the first stage exploded soon after taking off. This one worked. The issue in liquid-fueled rockets is whether the designer can scale up motors to the desired power (the Russians clustered lower-powered rockets to avoid this problem). Motors can, for example, vibrate themselves to pieces.