North Korean leader Kim Jong-Un ordered his frontline troops onto a war-footing from Friday, as military tensions with South Korea flared following a rare exchange of artillery shells across their heavily fortified border.
The North's official KCNA news agency said the move came during an emergency meeting late on Thursday of the powerful central military commission of which Kim is the chairman.
During the meeting, Kim ordered frontline, combined units of the Korean People's Army (KPA) to "enter a wartime state" from Friday 5:00pm (0800 GMT).
The troops should be "fully battle ready to launch surprise operations" while the entire frontline should be placed in a "semi-war state," KCNA quoted him as saying.
The CMC meeting came hours after the two Koreas traded artillery fire on Thursday, leaving no apparent casualties but pushing already elevated cross-border tensions to dangerously high levels.
North Korea followed up with an ultimatum sent via military hotline that gave the South 48 hours to dismantle loudspeakers blasting propaganda messages across the border or face further military action.
The ultimatum expires at Saturday, 5:00pm.
The South's defence ministry dismissed the threat and said the broadcasts would continue.