North Korea on Saturday made a fresh vow to build up its nuclear deterrent in the face of "threats of war" from the United States and a "policy of confrontation" from South Korea.
An editorial in Pyongyang's ruling party daily, the Rodong Sinmun, said "reckless" war exercises by the US and South Korea could spark a nuclear war at any moment.
"As long as the United States and South Korean puppets continue with nuclear threats and threats of war against us, we will ... strengthen [our] nuclear deterrence through every possible means," it said.
South Korean President Park Geun-Hye is no different from her predecessor in policy orientation, the editorial said, accusing the South of deliberately sabotaging planned high-level talks.
"Unless there is a fundamental switchover in the policy of confrontation of the South's ruling forces, dialogue and improvement in relations between the North and the South cannot be realised forever," it said.
The two Koreas had agreed to hold their first high-level talks in six years in Seoul on Wednesday and Thursday, but the talks were called off at the last minute following a dispute over protocol.
The talks initiative had been seen as a step forward after months of soaring military tensions, with the North conducting its third nuclear test in February. Their collapse is a sizeable backwards stride.
The editorial was dedicated in commemoration of a landmark summit between the two Koreas on 15 June 2000, which led to a short-lived reconciliation and exchanges between the two Koreas.
Glyn Davies, the US pointman on North Korea policy, said Friday that the United States was exasperated with Pyongyang after it snubbed attempts by President Barack Obama's administration to reach out in 2009 and again in 2012.
"The United States will not accept North Korea as a nuclear-armed state. We will not reward the DPRK for the absence of bad behavior," Davies said, using the North's official name of the Democratic People's Republic of Korea (DPRK).
Davies repeated US calls on North Korea to take steps to end its nuclear weapons programme in line with previous agreements.