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South Korea rejected North Korea's offer to take a series of steps to ease tension that included canceling Seoul's regular military drills with Washington, saying Friday that Pyongyang must take nuclear disarmament steps first.

The North's powerful National Defense Commission on Thursday proposed the rivals halt military actions and mutual vilification to build better relations. The North, however, strongly hinted it would maintain its nuclear weapons program and urged South Korea to cancel its upcoming springtime drills with the United States.

The North's overture is a sharp departure from its repeated threats of nuclear strikes against Seoul and Washington that raised tensions a year ago. Analysts say Kim Jong Un's government hopes that improved ties with South Korea could help attract foreign investment to boost the communist nation's lagging economy.

On Friday, South Korea said it would press ahead with the drills which it says are defensive in nature and demanded that North Korea take "practical" actions for nuclear disarmament if it truly wants peace on the peninsula.

"North Korea should keep in mind that trust between South and North Korea is something that can be demonstrated with action, not by words," Unification Ministry spokesman Kim Eui-do told reporters.

The North's statement, which came after leader Kim called for improved ties in his New Year's Day message, proposed the Koreas stop slandering each other on Jan. 30, a day before Lunar New Year's Day which is celebrated by both sides. The North also said it will first take steps to halt acts of provoking South Korea near the disputed western sea boundary, the scene of several bloody skirmishes between the Koreas in recent years, and in other areas.

South Korea's Defense Ministry said Friday it would "unsparingly" punish North Korea if it uses the South Korea-U.S. drills as a justification for any provocation. Spokesman Kim Min-seok said that South Korea will continue to bolster its defenses around front-line islands near the sea boundary.

Kim Yong-hyun, a professor of North Korea studies at Seoul's Dongguk University, said North Korea is likely to respond to Seoul's rejection by increasing the level of its rhetoric but not with actual force. "For the time being, South-North relations will be like walking on thin ice" until the South Korea-U.S. drills end, he said.

Koh Yu-hwan, a North Korea expert at the same university, said the North's proposal appears to be aimed at setting the groundwork for blaming South Korea for tensions between the countries in the future. "I don't think North Korea made these proposals believing that South Korea would accept them," he said.

North Korea has made similar conciliatory gestures in the past to win concessions and aid after stoking tensions. Last year, North Korean leader Kim also talked about improved ties with South Korea in his New Year's Day message, but followed that with a nuclear test in February and threats of nuclear war in the following months.