Pyongyang, North Korea - North Korean leader Kim Jong-un vowed to deal a "death-blow" to his country's enemies, state media said Thursday, as South Korea's hawkish ruling party suffered a defeat in parliamentary elections.

So far this year, the nuclear-armed North has declared South Korea its "principal enemy," closed agencies dedicated to reunification and outreach, and threatened war over "even 0.001 millimeters" of territorial infringement.

If provoked, North Korea will "deal a death-blow to the enemy without hesitation by mobilizing all means in its possession," Kim said, according to Pyongyang's official Korean Central News Agency (KCNA).

He made the remarks during a visit to the Kim Jong Il University of Military and Politics on April 10, the same day as South Korea's parliamentary election, KCNA said.

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"Now is the time to be more thoroughly prepared for a war than ever before," Kim said.

North Korea must be "firmly and perfectly prepared for a war, which should be won without fail, not just for a possible war."

Partially blurred images released by state media depicted Kim, surrounded by army officials, inspecting what appeared to be a miniature of South Korea's capital Seoul, including its Han River, along with maps of the peninsula.

South Korea's parliamentary election result handed a defeat to the party of incumbent President Yoon Suk Yeol, who has taken a belligerent line with the nuclear-armed North while improving ties with Washington.

It also makes him a likely lame duck for his remaining three years in office.

The main opposition Democratic Party, which won by a landslide, favors a softer approach towards Pyongyang.