Sources are telling CNN that North Korean engineers are working on upgrading an existing ICBM to make it capable of striking the United States.

Pyongyang is working to upgrade a KN-20 ballistic missile less than six months after first testing an ICBM. Sources said the missile development is part of an accelerated effort by leader Kim Jong-un to develop weapons capable of threatening the United States.

The ramped up develop is also causing U.S. military and political officials to reassess their options for dealing with North Korea.

U.S. officials have said they believe North Korea will be capable of miniaturizing a nuclear warhead so it can be mounted atop an improved ICBM sometime during 2018.

Analyst comment: The closer North Korea gets to perfecting a nuclear weapon that can threaten the United States, the closer the Trump administration gets to launching preemptive military action against Pyongyang. 

Why it’s on our radar: Information in this article helps satisfy Priority Intelligence Requirement 3: What are the latest indicators of a U.S.-North Korea war?  Each week in our Strategic Intelligence Summary, we gauge the likelihood and scope of conflict with Russia, China, North Korea, and in the Middle East, and track the latest developments in each region.  Subscribe here to receive our premium intelligence products prepared by Intelligence and special operations veterans.