SEOUL, South Korea (AP) - New satellite images show construction under way at North Korea's main atomic complex, apparent proof that Pyongyang is making good on its pledge to build a nuclear power reactor, according to a private American security institute.
North Korea vowed in March to build a light-water reactor using its own nuclear fuel, and two American experts who recently visited the North have reportedly said that construction has begun.
Light-water reactors are ostensibly for civilian energy purposes, but the power plant would give the North a reason to enrich uranium. At low levels, uranium can be used in power reactors, but at higher levels it can be used in nuclear bombs. While light-water reactors are considered less prone to misuse than heavy-water reactors, once the process of uranium enrichment is mastered, it is relatively easy to enrich further to weapons-grade levels.
North Korea is pursuing an arsenal of atomic weapons, so all its nuclear projects are of intense interest to its neighbors and to the United States. It carried out nuclear tests in 2006 and 2009, drawing international condemnation and U.N. sanctions.
The Washington-based Institute for Science and International Security on Thursday released commercial satellite images from Nov. 4 that show a rectangular structure being built, with at least two cranes visible at the complex. It estimated North Korea was constructing a 25 to 30 megawatt light-water reactor.
The institute based its estimate on information from the recent trip to Yongbyon by Siegfried Hecker, former director of the U.S. Los Alamos Nuclear Laboratory, and Jack Pritchard, a former U.S. envoy for negotiations with North Korea.
It said Hecker told the institute "that the new construction seen in the satellite imagery is indeed the construction of the experimental light-water reactor."
The institute said the amount of low-enriched uranium needed for a 25 to 30 megawatt reactor could vary "depending on the design of the reactor and whether it will be optimized for electricity production or weapon-grade plutonium production."
South Korean Foreign Ministry spokesman Kim Young-sun said the construction has yet to be verified and that Seoul was monitoring developments at the site and talking with other countries. Kim said any move to build a light-water reactor would violate U.N. resolutions on North Korea aimed at reining in its nuclear programs.
In Washington, U.S. State Department spokesman P.J. Crowley called on North Korea to live up to its commitment to denuclearize.
"North Korea is not pursuing a civilian nuclear program by itself. It is a proliferator. It has a military program," Crowley told reporters.
Still, he said Washington is prepared to have a conversation about how to meet North Korea's legitimate energy needs if Pyongyang takes affirmative steps to denuclearize.
The new satellite imagery comes as North Korea presses for the resumption of international nuclear disarmament talks it quit last year. South Korea and the United States have said North Korea must show its sincerity before those talks can continue.
Washington promised the energy-starved North two light-water reactors under a 1994 deal meant to freeze North Korea's plutonium program. The deal, however, collapsed in 2002 when the United States accused North Korea of running a secret uranium enrichment program - a process that would give it a second way to build nuclear bombs in addition to the plutonium program.
After seven years of adamant denials, North Korea said last year that it was in the final stages of uranium enrichment.
The Choson Sinbo, a pro-North Korean newspaper in Japan, reported Thursday that Pyongyang was building a light-water reactor as part of its plan to revive its economy ahead of 2012, the 100th anniversary of the birth of the country's founder, Kim Il Sung, father of current leader Kim Jong Il.