Nuslear security

North Korea threatens nuke strike on Washington

North Korea released a video Saturday threatening a nuclear attack on Washington, D.C., and also warned that its military is ready to attack Seoul's presidential palace unless South Korean President Park Geun-hye apologizes for "treason" and executes officials responsible for what Pyongyang says are plans to attack its leadership.

A four-minute video, titled "Last Chance," shows animated scene in which a submarine fires a missile through clouds, before it crashes near the Lincoln Memorial, triggering an explosion that destroys the city.

"If the American imperialists provoke us a bit, we will not hesitate to slap them with a pre-emptive nuclear strike," the message says.