Amid the latest series of North Korean missile tests, South Korea's Ministry of Unification has asserted that Pyongyang is ready to carry out its fifth nuclear weapons test detonation and may simply be waiting for a politically advantageous time to do so. But if the North wants to further bolster the credibility of its claims to possess a long-range nuclear deterrent, it will need to do at least two more things: conduct active re-entry tests to verify the viability of a nose cone and conduct a test of a guidance system for re-entry. Pyongyang is not seeking to match current U.S., Russian or Chinese technologies. It is sufficient to demonstrate technologies from the 1950s and 1960s -- technologies that have been amply documented, studied and tested....