US intelligence has detected an explosion of less than one kilotonne in magnitude in North Korea but has not been able to determine whether it was nuclear or not, a senior intelligence official said.
The official, who asked not to be identified, said that first-time nuclear tests historically have been in the several kilotonne range.
“We are aware that there was a sub-kilotonne explosion in North Korea,”? said the official. “We have not been able to determine at this point whether it was in fact nuclear.”?
Unusual activities were detected in a rugged area in North Korea on Monday, causing South Korean authorities to suspect that the communist state might be preparing a second nuclear test, a news report said.
Kim Seung-Gyu, head of South Korea’s spy agency, told parliament that activity involving vehicles and some 30 to 40 people was under way at Punggyeri in the northeastern county of Kilju, Yonhap news agency reported.
“From three p.m. (06:00 GMT) today, there have been some unusual movements under way at Punggyeri where we had thought the first nuclear test would be carried out,”? Kim was quoted as saying.
“We have been closely following developments there to find out whether North Korea is moving to conduct a series of tests as India and Pakistan did,”? he said.
An unidentified lawmaker who serves on parliament’s intelligence committee quoted Kim as telling the committee that there is a “?sufficient possibility”? of the North carrying out further nuclear tests.
Punggyeri is where vehicle movements and the unloading of large reels of cable were spotted by satellite images last month, prompting speculation that a nuclear test was being prepared.
Punggyeri is some 30 kilometers (20 miles) northeast of Hwadaeri, where South Korean officials said Monday’s test appeared to have been carried out.
Kim was also quoted as saying that North Korea is believed to have stored up to 40 kilograms (88 pounds) of plutonium, enough to make as many as seven nuclear bombs.
“North Korea is believed to have stored some 30 to 40 kilograms of plutonium,”? he was quoted as telling the intelligence committee.
Chung Hyung-Keun, an opposition Grand National Party lawmaker who serves on the committee, quoted the intelligence chief as making the plutonium comments.
The 40 kilograms includes 10-12 kilograms that it had secured before it opened its nuclear facilities in Yongbyon, 90 kilometers (56 miles) north of Pyongyang, to International Atomic Energy Agency inspectors, Kim said.
“As one bomb needs five to six kilograms of plutonium, North Korea would be able to make up to seven atomic bombs,”? Chung told journalists.
“We cannot rule out the possibility of the North carrying out further nuclear tests as Pakistan, for example, carried out six nuclear tests,”? he said.
Pakistan was the last nation, in May 1998, to conduct a nuclear weapons test.