A U.S. think tank predicts North Korea is nearly ready to resume producing weapons-grade plutonium at its nuclear facility in Yongbyon within as little as one to two months.

The U.S.-Korea Institute at the Johns Hopkins School of Advanced International Studies released a report Monday on the Web site 38 North saying it reached the tentative conclusion based on commercial satellite images taken May 22nd.

The report said Pyongyang is nearing completion of work necessary to restart its 5-megawatt gas-graphite reactor used in the production of North Korea’s supply of weapons-grade plutonium.

However, the institute said the availability of fresh fuel rods to power the reactor remains uncertain.

In early April, Pyongyang publicly declared it will produce nuclear weapons and annul the six-party talks' agreement.