He didn't. Blame Pakistan, the Soviets, and the Chinese.
More recently, blame the South Koreans (the KDJ and RTW administrations) and the Chinese for harboring the viper. US hands have been tied (other than in case of a truly grave and imminent crisis) for nearly a decade.
Clinton didn't do what he could have when he had a chance to, given a cooperative South Korean government of the day, but thats water long under the bridge.
Clinton gave them the technology for nuclear power, yet never followed up to make sure they were not enriching uranium. They trusted the NK's at face value and failed us.