The reports from South Korea's intelligence services could not yet be independently verified. But they have kicked off a debate about Kim Jong-un's grip on power.
North Korea went on high alert and said the US should forgo planned military exercises with Japan and South Korea. But it could have a hidden agenda.
Defense Secretary Hagel's comments about the North's chemical arsenal come amid new concerns over the sophistication of North Korea's nuclear weapons program.
When North Korea shut down the industrial park it jointly maintained with South Korea in April, it ratcheted tensions to a new high.
Analysts say that North Korea may be holding out for a high-profile visitor from the US before allowing Kenneth Bae’s release.
North Korea missiles: Cuba says the 240 tons of weapons were being sent to North Korea for repairs. Many international observers are dubious.
On the 63rd anniversary of the Korean War that divided the peninsula, hackers hit systems in both North and South Korea.
North Korea's refusal to take South Korea's phone calls has dashed hopes for proposed peace talks.
Relations between the North and the South have been more strained than usual lately, but an agreement to discuss reopening a joint factory venture could shift the mood in the region.
Only one prisoner born in North Korea's gulag is known to have escaped to tell his story. A Q&A with Blaine Harden, the journalist who wrote about Shin Dong-hyuk.