North Korea’s leader Kim Jong-un orders the country’s nuclear arsenal prepared for use at any time and the military to be in "pre-emptive attack" mode, citing growing threats from enemies.
The order announced on Friday came a day after the UN approved its harshest sanctions crafted by the US against the impoverished nation, marking a further escalation of tension on the Korean peninsula.
The official KNCA news agency said under Kim's order, nuclear warheads must be “on standby so as to be fired at any moment.”
He issued the order while supervising military exercises involving newly developed rocket launchers, the news agency added.
Kim said the situation had become very dangerous following the adoption of the sanctions, which came just days ahead of joint military drills by the US and South Korea.
Pyongyang views the drills as provocative rehearsals for an invasion.
North Korea launched several projectiles into the sea about 150 kilometers (90 miles) off the South Korean coast on Thursday in an apparent response to the new sanctions.
Following the adoption late Wednesday of the US-engineered sanctions, South Korean President Park Geun-hye warned of a "fiercer" North Korean backlash than normal.
On Friday, however, Park promised a harsh response to any military provocation by North Korea.
"If North Korea launches a provocation, we must respond with stern punishment to clearly show the price North Korea has to pay and our determination to protect our nation," she said in a televised speech.
South Korea and the US were to hold talks on Friday on details of a possible deployment of THAAD, an advanced US missile system, to counter possible threats from Pyongyang.
China has voiced concerns that the X-band radar to be deployed with the THAAD system had a range that extended far beyond the Korean peninsula into the interior of China.
North Korea launched a long-range rocket last month carrying a satellite. South Korea, other neighbors and Washington denounced the launch as a missile test.
North Korea accuses the US of plotting with its regional allies to topple the government in Pyongyang. The country bills its nuclear capabilities as a deterrent against hostile US policies.
Pyongyang also wants Washington to dissolve its military command in South Korea, where the US has thousands of troops.