North Korea is close to restarting the formerly shuttered Yongbyon nuclear reactor, a new analysis by a US thinktank suggests. Once fully operational, the plant could produce about 6 kilograms of the plutonium — a key component in nuclear weapons — per year.

The report, released by the 38 North website in affiliation with the US-Korea Institute at John Hopkins University, analyzed commercial satellite imagery to confirm that North Korea is "making important progress in activating key nuclear facilities at Yongbyon, including the 5 MWe gas-graphite reactor and the 20-30 MW(th) Experimental Light Water Reactor (ELWR)."

The report also found that imagery of a shipment yard nearby by the sites showed considerable recent activity, indicating that construction efforts are stepping up.

It predicts that the reactor could be up and running in just one or two months, so long as North Korea has access to fuel rods to power it.

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"North Korea may not be testing long-range missiles or nuclear weapons right now but its WMD program is moving ahead," 38 North editor and former State Department official Joel Wit told the Associated Press.

"The purpose of restarting the five megawatt reactor is crystal clear: the production of more plutonium for more bombs," Wit said.

South Korean Defense Ministry spokesman Kim Min Seok said Tuesday that he felt the one-to-two month estimate was "a bit too early," and added that his nation was also monitoring activity at the site.

The reactor has been shuttered since the summer of 2007, when the North agreed to close it in a disarmanent-for-aid agreement.

The following year authorities demolished Yongbyon's nuclear cooler, a move many in Washington considered to be a victory. But some analysts in Seoul, such as Kookmin University's Andrei Lankov, warned that the country's nuclear program was non-negotiable, and that the country would eventually restart the mothballed plant.

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North Korea has maintained that it needs nuclear weapons to defend itself against so-called aggression from the United States. The nation exists in a constant state of military emergency, and many scholars have told GlobalPost that a nuclear program is the ultimate symbol of national glory, and probably carry popular backing inside the country.

Under Kim Jong Un, the North Korean government is adjusting its "military-first" policy, which upheld the military at the forefront of the nation. The government has iterated, through the state-run KCNA, that it is pursuing a model of economic development alongside the primacy of the military.

The continued emphasis on national defense could explain why North Korea in April announced that it would restart the Yongbyon reactor, analysts say.

Geoffrey Cain contributed to this report from Seoul, South Korea.