Scientist also accused of giving nuclear know-how to Libya, North Korea; was placed under effective house arrest in 2004 after admitting he shared tech with the 3 rogue nations

Pyongyang says new defense alliance 'will upset the strategic balance in the Asia-Pacific region,' accuses US of destabilizing region

Experts say development indicates regime will increase production of weapons-grade uranium at the Yongbyon site by as much as 25%

IAEA reports activity at the Yongbyon reactor, which had been inactive since December 2018; Washington closely coordinating with partner countries, senior US official says

Coal-fired steam plant at Yongbyon nuclear complex back in operation after 2-year break, analysts say, though it could just be being prepped to handle radioactive waste

With Biden set to take office, North Korean leader insists US policy toward Pyongyang 'will never change, whoever comes into power'

Kim Jong Un says he won’t use his nuclear weapons first, suggests he's open to dialogue, but also calls Washington his 'main enemy'

Kim Jong Un has threatened to take unspecified action if sanctions are not eased by year's end; speculation has centered on possibility of nuclear warhead test

Pyongyang doesn't specify what was tested but says it will further boost its 'reliable strategic nuclear deterrent'

Pyonpang's negotiator says talks collapsed because 'US has not discarded its old stance and attitude'; State Dept: Comments don't reflect the 'good discussions'