美韩研究所：朝鲜核反应堆可能恢复运作

A Washington-based research group says North Korea has likely restarted a plutonium reactor, possibly making good on a pledge to expand its nuclear weapons program.

The U.S.-Korea Institute at Johns Hopkins University based its conclusion on recent satellite photos that appear to show white steam emerging from a building near the reactor at the North's main Yongbyon nuclear complex.

The reactor was shut down in 2007 under an aid-for-disarmament deal. But in April, Pyongyang warned it would restart all operations at Yongbyon to boost its nuclear force in both "quantity and quality."

The institute's researchers say the color and the volume of the white steam seen emerging from the building in the August 31 commercial satellite photos suggest the reactor has been put back into operation.

South Korean officials say they are still working to find out if the reactor has been restarted.