North Korea has yet to master the skills needed to make nuclear warheads small enough to fit onto inter-continental ballistic missiles, Vice Defense Minister Baek Seung-joo said Wednesday.

   In the massive military parade marking the ruling party's foundation anniversary last Saturday, North Korea displayed the KN-08 ICBMs tipped with a round warhead alongside 30 other types of weapons.

   The North introduced the missiles in the parade as one of the "diversified and miniaturized" strategic rockets loaded with nuclear warheads, although South Korea's Defense Ministry could not confirm their authenticity.

   North Korea's tests of nuclear bombs and long-range rockets in recent years have spawned speculation that the country may have acquired the technology to make nuclear-armed ICBMs.

   "Our assessment does not indicate (North Korea) has reached the level of loading (nuclear warheads onto ICBMs)," Baek said in a parliamentary questioning.

   If North Korea successfully loads a warhead onto the KN-08 ballistic missile with a range of about 12,000 kilometers, it could put the U.S. West Coast within the range of nuclear attack.

   "North Korea has done several nuclear tests and we are concluding that they have made progress in the miniaturization skill," Baek said.

   Asked to confirm if North Korea could take as long as seven years to finish miniaturization as other nuclear-possessing countries do, Baek said seven years is the average time needed for the task.

   The Defense Ministry is closely watching the progression of North Korea's related skills, he added. (Yonhap)