"The threat level has jumped" following the nuclear test, said Narushige Michishita, a former Ministry of Defense official and director of the Security and International Studies Program at Tokyo's National Graduate Institute for Policy Studies.
Unlike North Korea's still-under-construction intercontinental ballistic missile, or ICBM, program, its arsenal of about 300 deployed Rodong missiles has been flight tested and is thought to have a range of about 1,300 kilometers (800 miles).
That is good enough to reach Tokyo and key U.S. military bases — including Yokota Air Base, which is the headquarters of the U.S. 5th Air Force; Yokosuka Naval Base, where the USS George Washington aircraft carrier and its battle group are home-based; and Misawa Air Base, a key launching point for U.S. F-16 fighters.
Michishita, in an analysis published late last year, said a Rodong missile launched from North Korea would reach Japan within five to 10 minutes and, if aimed at the center of Tokyo, would have a 50-percent probability of falling somewhere within the perimeter of Tokyo's main subway system.
He said Japan would be a particularly tempting target because it is close enough to feasibly reach with a conventionally or nuclear-armed missile, and the persistent animosity and distrust dating back to Japan's colonization of the Korean Peninsula in 1910 provides an ideological motive.
Also, a threat against Japan could be used to drive a wedge between Tokyo and Washington. North Korea could, for example, fire one or more Rodong missiles toward Tokyo but have them fall short to frighten Japan's leaders into making concessions, stay out of a conflict on the peninsula or oppose moves by the U.S. forces in Japan to assist the South Koreans, lest Tokyo suffer a real attack.
"Given North Korea's past adventurism, this scenario is within the range of its rational choices," Michishita wrote.