A missile launched toward Japan by the reclusive nation soared to new heights, achieving a technological advance after a series of failures.
News of the test launch comes ahead of the ruling Workers' Party congress, where Kim Jong-Un Is expected to flaunt his leadership and North Korean military might.
South Korea's ruling conservatives have lost their legislative majority at a time of growing tensions with North Korea, in a move that could jeopardize ongoing attempts at economic reforms.
An unnamed official told Yonhap news agency that the North Korean army colonel specialized in anti-South espionage operations and this was the highest-level military figure ever to have defected.
On Wednesday the UN agreed its toughest ever sanctions against North Korea, effectively creating a blockade of the already-isolated nation. Hours later, Pyongyang launched a volley of missiles.
The war of words between the North and South has been escalating since Pyongyang's nuclear test in January and a long-range rocket launch two weeks ago.
An unnamed Japanese government official cited signs of possible preparations for a missile launch, based on analysis of satellite imagery of the North's Tongchang-ri missile test site.
Pyongyang has responded to Seoul's loudspeaker broadcasts by dropping leaflets that threaten attacks and compare South Korea's president to a zombie.
If North Korean refugees traveling through China can make it across the border to Southeast Asia, freedom — in the form of political asylum and a ticket to South Korea — is typically the outcome. This case was not typical.
The elderly South Korean was hospitalized with third degree burns and breathing difficulties, after he set himself ablaze outside the Japanese embassy in Seoul on Wednesday.