The conclusion was based on North Korea's "current estimated weapon yields," author Michael J. Zugarek wrote in an October 4 post. The researcher says that a single 250-kiloton-yield warhead detonated over the two Asian cities would also result in approximately 7.7 million injuries.
The author assumes North Korea to have 25 nuclear weapons. The terminal high-altitude area defense (THAAD) system in South Korea would intercept some of them, the author seems to assume, while other missile defense features in Japan would also take down some of the incoming threats. Tokyo does not yet have an Aegis Ashore land-based missile defense system but is in the process of acquiring one, the report states.
The Lockheed Martin product is a version of the naval Aegis Combat System, "a sophisticated collection of phased-array radars, fire control directors, computers and missiles" according to the company's description, with elements typically mounted on guided missile cruisers.
Stanford University's Siegfried Hecker has estimated that North Korea's nuclear stockpile sits at about 25 warheads. Further, Hecker has projected that Pyongyang can add six or seven nukes to its cache per year, Sputnik reported.
All 25 million residents of North Korea, however, are easily reachable by America's roughly 6,800 nuclear weapons.