North Korea to resume nuclear activity?

Steam was spotted rising from North Korea's Yongbyon nuclear facility, suggesting that the reactor has been restarted, a US institute says.

The colour and volume of the steam indicated that the reactor was in or nearing operation, the institute said.

The reactor can produce plutonium, which North Korea could use to make nuclear weapons.

It is believed North Korea already possesses between four and 10 nuclear weapons, based on plutonium produced at the Yongbyon reactor prior to mid-2007, when the facility was closed down.

The report was written by the US-Korea Institute at Johns Hopkins University. The institute uses satellite imagery to monitor developments in North Korea.

The reactor uses steam turbines to generate electricity, and the steam seen in satellite imagery from 31 August indicated that the electrical system was about to come online, the report said.

Putting them in a position to increase the amount of material they have for nuclear weapons, North Korea will gain some more leverage in negotiations, and adds a sense of urgency on the US part.

The five megawatt reactor can produce spent fuel rods that can be made into plutonium, which experts believe North Korea used for its nuclear tests in 2006 and 2009. North Korea conducted its third, most-recent test in February, but it is not clear whether plutonium or uranium was used.