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

Satellite images reveal construction in area adjoining plant at Yongbyon, 'heart' of hermit kingdom's nuclear program

Military says projectiles hit targets as part of Pyongyang’s efforts to diversify launch options; South Korea reports 1st test of submarine-launched ballistic missile

The launch comes two days after North claims to have tested a newly developed cruise missile, in a sign of pressure on Washington

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

Top Pyongyang official says US to face 'grave situation' after US president called its nuclear program a 'serious threat' to US and world security in Congress speech last week

US asks for meeting of UNSC committee monitoring sanctions against Pyongyang, which'll take place behind closed doors; new weapon’s warhead weight improved to 2.5 tons

Japan says launches a threat to regional peace and safety; Pyongyang also fired short-range weapons presumed to be cruise missiles over the weekend

But Washington downplays action as 'common' military testing, claims Pyongyang didn't violate Security Council resolutions; launches follow joint US-South Korean military exercises

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