The assessment in an unclassified report to Congress gels with another recent analysis of Pyongyang's missile programs by the Defense Intelligence Agency, made public last week, and will fuel fears the Stalinist state may end its missile test moratorium.
"The multiple-stage Taepo Dong-2 capable of reaching parts of the United States with a nuclear weapon-sized payload may be ready for flight-testing," the Central Intelligence Agency said in the report, which analyses weapons of mass destruction production for the first six months of 2003.
It is not the first time that the CIA has warned that Pyongyang may have reached the flight-test stage for the Taepo-Dong 2, but concern is growing with the Stalinist state locked into a nuclear showdown with Washington.
The agency said in previous reports that in a regular two-stage set up, the Taepo Dong-2 could deliver a payload of several hundred kilograms to Alaska, Hawaii and parts of the continental United States.
In an adapted three-stage configuration, the Taepo Dong-2 could in theory ferry a warhead to anywhere in North America.
North Korea has said it will stick to its missile moratorium until the end of this year, but yet to commit to extending it into next year.
Pyongyang's missile program has long worried the United States, and states like South Korea and Japan which are within range of its short and medium range missile arsenal.
Washington has also warned at North Korea's propensity to export missile technology and other ingredients of weapons of mass destruction.
The administration of president Bill Clinton strove to seal a pact with Pyongyang to end its missile program in the dying days of his administration in 2000, but the deal foundered on how it would be verified.