Vapor coming out of reactor cooling tower in Yongbyon Nuclear Center in Pyongyang on Jan. 7 (above) is not seen in the picture taken April 7.

But a U.S. official said there could be at least two other possibilities: that the reactor had run into mechanical trouble or that North Korea was engaging in a game of bluff.

The plant at Yongbyon houses a 5-megawatt reactor that generates spent fuel rods, which must be removed and reprocessed to extract plutonium. This can only be done after the reactor has been shut down.

North Korea restarted the reactor after expelling U.N. monitors at the end of 2002. The shutdown was detected by what U.S. analysts refer to as "overhead imagery," which could involve spy satellites.

The New York Times reported April 18 that the apparent shutdown of the reactor has raised concerns at the White House that North Korea could be preparing to make good on a recent threat to harvest a new load of nuclear fuel, potentially increasing the size of its nuclear arsenal.

Three rounds of six-nation talks on the North's nuclear ambitions have produced no breakthroughs, and Pyongyang announced in February that it had developed atomic weapons and would indefinitely boycott the negotiations.

The Japan Times Weekly: April 23, 2005
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