North Korea has announced plans to restart its mothballed nuclear facilities.
In a move that will add to recent tensions, Pyongyang said all facilities at its main Yongbyon nuclear complex, including a reactor mothballed in 2007, would be restarted.
It is the latest measure from North Korea since it carried out a nuclear test in February.
When fully running, the reactor is capable of churning out one atomic bomb worth of plutonium — the most common fuel in nuclear weapons — a year.
The facility was mothballed in 2007 as part of nuclear disarmament negotiations.
South Korea said the announcement would be "highly regrettable," the BBC reported.
A North Korean statement said the move was needed to generate more electricity.
But it will fuel fears of Pyongyang's push for technology to allow missiles to reach the United States.
North Korea's third nuclear test prompted tough UN sanctions that ramped up the current tensions. The US responded by sending military aircraft to South Korea.
It has always claimed the nuclear technology is aimed at generating electricity.