U.N. Secretary General Ban Ki-moon on Tuesday urged North Korea to avoid any actions that might escalate military tensions as South Korea's president spoke again of a "reign of terror" in the North's capital, Pyongyang.

Speaking at an Asian Leadership Conference in South Korea's capital, Seoul, Ban said the divided Korean peninsula remained one of the world's most dangerous flashpoints.

South Korean President Park Geun-Hye warned Monday that North Korea's recent submarine-launched ballistic missile test posed a "serious challenge" to regional stability and vowed a strong military response to any provocation from Pyongyang.

Pyongyang's state media announced Saturday that a new SLBM had been successfully tested under the personal supervision of North Korean leader Kim Jong-Un, who described it as a "world-level strategic weapon".

In a rare display of political unity, South and North Korea on Thursday both condemned Japanese Prime Minister Shinzo Abe for failing to apologize during a U.S. visit for the wartime use of sexual slaves.

Their respective foreign ministries each issued statements criticizing Abe for distorting history, with Pyongyang comparing the Japanese leader to "psychopaths" and "hooligans".

North Korea has increased its "material support" for terrorist organizations and should be placed back on America's list of nations that are state sponsors of terrorism, a report released Monday said.

The Pyongyang regime, at the time under the command of Kim Jong-il, was taken off the list in 2008 under the presidency of George W. Bush, who hoped to engage the reclusive nation in dialogue. 

North and South Korea dug in their heels Friday in an escalating row over wages at their Kaesong joint industrial zone.

Pyongyang last month announced it would raise the basic salary of some 54,000 North Korean workers employed across 125 South Korean firms in the complex.

North Korea has told the United Nations that its call to refer Pyongyang to the International Criminal Court is invalid after a prominent defector retracted part of his testimony to a U.N. rights inquiry.

North Korea made the argument in a letter dated Wednesday from Ambassador Ja Song Nam to the U.N. General Assembly and Secretary-General Ban Ki-moon.

North Korea threatened Wednesday to reconsider proposals for dialogue with South Korea, condemning this week's propaganda balloon launch by U.S. and South Korean activists as an "intolerable" provocation.

The threat came two days after North Korean defectors led by Park Sang-Hak teamed up with activists from the U.S.-based Human Rights Foundation to launch some 100,000 anti-Pyongyang leaflets over the border by balloon.

South Korean President Park Geun-Hye said Monday she was willing to meet unconditionally with North Korean leader Kim Jong-Un, and urged Pyongyang to respond more "proactively" to Seoul's offer for dialogue.

Park, in her New Year's press conference, added she was willing to "meet just about anyone" to ease tension on the peninsula and seek eventual reunification. 

North Korea suffered a new Internet outage on Saturday shortly after calling U.S. President Barack Obama a "monkey" over the release of a comedy film about a fictional plot to kill its leader.

The latest shutdown came after the isolated dictatorship's powerful National Defence Commission (NDC) threatened "inescapable deadly blows" over the film and accused the U.S. of "disturbing the Internet operation" of media outlets after a blackout earlier this week.

North Korea threatened Sunday to hit back at the White House and other U.S. targets if Washington sanctions it for an alleged hacking attack.