hankyoreh

North Korea is believed to have carried out its first-ever nuclear weapon test in the eastern part of the country Monday morning, a South Korean defense source said.

"We detected the explosive sound from Hwadaeri near Kilju in North Hamgyong Province at 10:36 a.m.(KST)," a senior Defense Ministry official said, asking to remain anonymous because of the sensitive nature of the information.

Later in the day, other defense and intelligence sources identified the test site as Musudanri in Hwadaegun, North Hamgyong Province.

Officials from the National Intelligence Service (NIS) said the test appears to have been conducted at a mountain close to a missile test site from where the communist state launched seven ballistic missiles in early July.

"We believe a nuclear test was conducted around 10:36 a.m. this morning and the (suspected) location of the test is about 30 kilometers away from Punggye-ri in Kilju" which intelligence officials had previously suspected to be a possible test site, an official from the state spy agency was quoted as telling the National Assembly Intelligence Committee.

"We believe the test was conducted under a mountain with an altitude of 360 meters," the NIS official was quoted by Rep. Chung Hyung-keun of the opposition Grand National Party as saying.

Considering the low altitude of the mountain, the intelligence office believes the nuclear test was conducted inside a horizontal tube instead of a vertically-dug tunnel, according to Chung.

South Korea's military raised its readiness against possible aggression by increasing the number of troops near land and sea borders, but it has yet to raise its alert level beyond usual defense situations, the Joint Chiefs of Staff (JCS) said. The troops are still maintaining a Watchcon 3 surveillance status and Defcon 4 defense readiness status.

"We have yet to detect unusual military movement in North Korea so far. South Korea and the U.S. are closely working together to share intelligence," said Col. Ha Doo-chul, spokesman for the JCS.

When tensions rise and provocative acts take place, the alert status is upgraded. In war, it is raised to Watchcon 1 and Defcon 1. In June 1999, when a naval battle between South and North Korea took place, the first of its kind since the end of the 1950-53 Korean War, South Korean forces were put on a Watchcon 2 surveillance status and Defcon 3 defense posture.

Seoul, Oct. 9 (Yonhap News)