U.S. scientists say that although North Korea has conducted nuclear tests on two occasions, its operational capabilities for nuclear weapons have yet to be verified.

The U.S. online magazine Bulletin of the Atomic Scientists says that despite the nuclear tests, North Korea has yet to demonstrate its real nuclear capabilities. The report says U.S. intelligence officials believe the North is not yet capable of loading nuclear warheads on missiles.

The magazine also referred to the North as a nuclear state.