North Korea is working on an advanced version of its existing KN-20 intercontinental ballistic missile that could potentially reach the United States, less than six months after it launched its first ICBM, a US official tells CNN. This newly assessed ICBM is just one part of an accelerated effort by Kim Jong Un’s regime to improve every part of its missile and nuclear weapons attack capability as quickly as possible,

according to several US officials familiar with the North Korean program. All of these improvements are forcing the US to recalculate the timing of the threat that a North Korean missile could pose to the US, and the need to continuously update US military response options. The officials spoke to CNN on the basis of anonymity because of the sensitivity of the issue, but all strongly emphasized that they were not discussing classified information. CONTINUE