i'm christine romans. >> i'm john berman. zoraida is off this week. it is thursday, april 4th. it is 5:00 a.m. in the east and we're going to start with the military situation. it seems ever more perilous this morning. warships launching, new missile defense systems deployed and the language getting flat-out dangerous. the korean peninsula might be the world's number one hotspot right now, the north threatening to block workers from the south from entering a shared industrial complex, even vowing to shut the facility down. pyongyang also promising attacks on the u.s. with a smaller, lighter and diversified nuclear force, and north korea also warns the moment of explosion is fast approaching. and will the pentagon announce it's moving a ballistic missile defense system to guam two years ahead of schedule, and there is also word out of washington this morning that it wants to try to dial down the rhetoric. we are all over this story this morning. dan lothian is live from washington, but we're going to begin in south korea with jim clancy.