A report by the U.S. Congressional Research Service says North Korea is likely to have one or two atomic bombs similar to the large-size plutonium bomb dropped by the U.S. on Nagasaki in August 1945.

Larry Niksch, an Asian affairs specialist for the research service, made the assessment in a report on North Korea’s nuclear weapons program posted to the CRS Website on August 1.

Niksch said the question of whether North Korea produced additional nuclear weapons with plutonium that it apparently acquired after 2003 may depend on whether the North can develop a nuclear warhead that could fit onto its missiles.

He added, however, that North Korea has few delivery systems that could reach a U.S. or Japanese target.

According to Niksch, Pyongyang probably wouldn't make additional Nagasaki-type bombs but would retain its weapons-grade plutonium until it could produce a nuclear warhead.