North Korea has detained for more than three weeks an 85-year-old American retiree who was on an organized tour due to an "misunderstanding," friends and relatives said Wednesday.

The U.S. special envoy on North Korea, Glyn Davies, without naming detainee Merrill Newman by name, called on North Korea to release Americans it is holding.

North Korea is believed to be capable of producing nuclear weapons from enriched uranium as well as from its existing plutonium stockpile, South Korea's defense minister said Wednesday.

"We evaluate that North Korea can produce nuclear weapons using uranium," Kim Kwan-Jin was quoted by Yonhap news agency as telling members of parliament.

A South Korean detained in North Korea for alleged espionage is a missionary who had been helping North Korean refugees hiding out in China, a fellow Christian activist said Wednesday.

The North earlier this month announced it had arrested a South Korean spy engaged in "plot-breeding" activities, but did not give his name.

U.S. Vice President Joe Biden thanked Panama Tuesday for detecting a controversial shipment of Cuban arms headed for North Korea apparently in violation of U.N. sanctions.

During his visit to tour an ongoing expansion of the Panama Canal, Biden said that the country "stepped up where others might have stepped back. ... You found and confiscated weapons heading from Cuba heading to North Korea.

At least 13 North Koreans have been arrested in the Chinese border city of Kunming on a secret journey to the South, media reports said Monday.

Chinese police on Friday arrested 13 North Korean refugees who were trying to board a bus bound to an unidentified Southeast Asian nation, Yonhap news agency said.

A leftist South Korean lawmaker on Tuesday denied charges of plotting an armed revolt in support of North Korea, calling himself the victim of a "witch hunt" by security authorities.

"I can say for certain that I've never plotted a rebellion," United Progressive Party MP Lee Seok-Ki said at the start of his sedition trial at a court in Suwon south of Seoul.

South Korea on Monday urged North Korea to identify a South Korean citizen it said it had arrested for espionage, as a newspaper report suggested the detained man was a missionary.

Pyongyang announced last week that it had arrested a South Korean spy engaged in "plot-breeding activities."

North Korea on Friday warned of "merciless" action to stop the alleged abduction of its citizens by South Korean spy agents and activists.

The North singled out South Korea's spy agency chief Nam Jae-Joon as the first target of its action.

North Korea said Thursday a South Korean spy has been arrested while trying to use "dishonest elements" for a mission to destabilize its social system.

Security authorities recently captured an agent of South Korea's intelligence service in Pyongyang, according to the North's official Korean Central News Agency (KCNA).

North Korea accused South Korean President Park Geun-Hye of "moral vulgarity" Wednesday after she suggested she was ready to hold a summit with its leader Kim Jong-Un at any time.

The North's Committee for the Peaceful Reunification of Korea accused Park of talking about a summit with Kim while making provocative remarks against Pyongyang.