Experts say it is unlikely Pyongyang will be able to see through project without external assistance, and that it is 'exaggerating' capabilities of sub

As tensions escalate, Pyongyang claims practicing 'scorched earth strikes' on its neighbor amid anger over joint US-South Korean drills

In end-of-year flurry of activity, Pyongyang eyes mass producing tactical nukes, developing more ICBMs; experts say North threatening action, peninsula could become '2nd Ukraine'

Pyongyang shoots ballistic missile into Sea of Japan as 'countermeasure' to military drills in South; South Korean president warns Kim Jong Un is gearing up for 7th nuclear test

Pyongyang accuses Washington of 'escalating the military tensions on the Korean peninsula'

South Korean and Japanese estimate that the ballistic missiles flew 220 to 250 miles at altitude of 20 to 30 miles before landing in waters between Korean Peninsula and Japan

Law will allow Pyongyang to carry out a preventive nuclear strike 'automatically' when a foreign country poses an imminent threat

Calling his country's atomic weapons a 'symbol of national power,' Kim vows to continue to develop capabilities 'at the fastest pace'

Analysts say work at Punggye-ri suggests Pyongyang could resume tests there, 4 years after declaring its closure ahead of Trump-Kim summit

Pyongyang is believed to be trying to pressure the US to resume stalled negotiations over its nuclear program