U.S. Defense Secretary Robert Gates claims that North Korea will be able to develop an inter-continental ballistic missile capable of reaching the U.S. mainland within five years. It is rare for a high-ranking U.S. government official to publicly present a time frame for such speculation. A North Korean ICBM would have to have a maximum range of between 8,000-10,000 km to reach the continental U.S., and no ballistic missiles it has deployed so far have this range. Currently the Musudan mid-range ballistic missile, deployed in 2007, has the longest range of 3,000-4,000 km, making it capable of reaching the U.S. territory of Guam.
The Taepodong-2 missile, which is under development, is believed to achieve the longest range of an estimated 6,700 km. That would put Alaska within range but not the continental U.S. North Korea conducted two test launches of the missile, but both failed. In July 2006, a Taepodong-2 missile exploded in flight, while in another test launch in April 2009, in which the North claimed it put a satellite into orbit, the three-stage rocket crashed into the Pacific 3,200 km from its launch site.
But although the missile failed to separate and fell short of its target, it was the farthest range achieved by a North Korean missile under development. Some experts say the Taepodong-2 could attain a maximum range of more than 8,000 km if the weight of its warhead is reduced, but there appear to be many obstacles left.
Gates appears to have been prompted by several factors to make his claim. First of all, North Korea has not conducted any missile tests since 2009 but continues to work on long-range missiles by testing engines at its research and development facilities in Musudan-ri and Tongchang-ri. The second factor is North Korea's missile link with Iran. The two countries are believed to have exchanged nuclear and missile technology, and North Korean ICBMs may have been tested in Iran, according to U.S. and South Korean intelligence. North Korea could speed up the development of ICBMs through help from Iran.