North Korea is giving no official indication it is preparing a third attempted nuclear test. But reports abroad say such an underground detonation could come at any time.
Some regional media outlets are reporting a North Korea nuclear test is expected between early and mid-May.
One report, in the Joong-Ang Ilbo in South Korea, quotes a diplomatic source in Washington as saying the United States has told South Korea such a detonation could occur as soon as this week.
Asked about that, a U.S. diplomat in Seoul replied the Embassy does not comment on “security matters.”
Diplomatic and intelligence sources, who do not want to be quoted, say they have seen no indication from satellite imagery that the equipment and associated cabling necessary to conduct such an underground detonation are in place. Images taken by surveillance satellites in the past few weeks did reveal that digging of a new tunnel was underway at the Pyunnge-ri test site.
There is growing speculation that North Korea will attempt to detonate a uranium-fueled weapon. Its previously announced tests, in 2006 and 2009, are widely believed to have used plutonium, although no traces of radioactive isotopes were detected following the second attempt.
At a briefing Monday, South Korean Defense Ministry spokesman Kim Min-suk told reporters preparations are underway to activate an emergency task force concerning a North Korean nuclear test, but it is not yet operational.
Kim says it is impossible to get precise information in real time about what is happening at the test site. But the South Korean military is utilizing various methods - in cooperation with U.S. forces - to collected pertinent information.
At the Unification Ministry, which is tasked with North-South relations as the two Koreas have no diplomatic ties, spokesman Kim Hyung-suk says there is concern North Korea could take further provocative actions soon, including another nuclear test.
The spokesman says the ministry is continuously asking Pyongyang to make a positive choice in responding to the active recommendations of the international community. Kim warns North Korea it can expect further punishment if it again carries out a provocation.
North Korea is already under international sanctions for previous nuclear and missile tests.
The United Nations Security Council, in the coming days, is expected to announce tighter sanctions in the wake of North Korea's April 13th rocket launch, which violated resolutions by the world body on the use of ballistic missile technology.
North Korea contends the launch, which failed two minutes after blast-off, was an attempt to place a peaceful satellite into orbit.
The embarrassing failure has been followed by increasingly belligerent rhetoric from Pyongyang, threatening “special military action” against the government of South Korea President Lee Myung-bak.
The North accuses President Lee of insulting it while the nation was grieving after the death in December of its leader, Kim Jong Il. North Korea accuses Mr. Lee of continuing to utter “unforgivable” insulting rhetoric during April while the country was marking the centennial of the birth of North Korea's founder and eternal President, Kim Il Sung.