North Korea: Significant movement of heavy machinery in North Korea could be a sign the secretive Stalinist state is gearing up for an underground nuclear test, according to US satellite intelligence reports.
The almost-daily reports of nuclear escalation in North Korea have a nerve-wracking effect on the region, underlining the threat the country poses and heightening tensions over the continuing nuclear standoff on the Korean peninsula.
Reports of a possible nuclear test came just days after North Korea test-fired a short-range missile into the Sea of Japan.
Officials in Asia and Washington have tried to play down the significance of the test. Military experts reckon that Pyongyang is developing ballistic missile technology to help it raise cash to keep the economy afloat as well as bankroll its nuclear ambitions.
Yesterday's reports were published in a South Korean newspaper, although experts in Washington and Seoul stopped short of saying there were definite signs the North Koreans were planning a test.
Quoting a government source, the Chosun Ilbo newspaper said US spy satellites had spotted frequent movements of trucks in the northeastern region of Kilju in North Korea, as well as the movement of cranes and other heavy equipment into the area.
"US intelligence authorities believe the images and other information point to preparations for a possible underground nuclear test," the report said.
The US has warned the International Atomic Energy Agency that North Korea has been preparing for an underground nuclear test since March and could carry it out as early as June.
In an effort to soothe raised tensions, South Korea's defence minister Yoon Kwang-ung told reporters before a meeting of the country's cabinet there were no unusual indications in the area.
North Korea announced in February it had nuclear weapons. Arms experts said it is not clear whether North Korea has the technology to build warheads small enough to mount on its missiles. The controversy over North Korea's nuclear ambitions dominated a United Nations global disarmament conference yesterday, where Washington urged Pyongyang to give up its nuclear ambitions.
US secretary of state Condoleezza Rice reminded North Korea that the United States has extensive military might in the Pacific which it could bring into play to "deter" North Korea's nuclear plans.
"I don't think anyone is confused about the ability of the United States to deter - both on behalf of itself and on behalf of its allies - North Korean nuclear ambitions or gains on the peninsula," she said.
"The United States maintains significant - and I want to underline 'significant' - deterrent capability of all kinds in the Asia-Pacific region, so I don't think there should be doubt about our ability to deter whatever the North Koreans are up to," she said.
The US has long-range missiles and heavy bombers within striking distance of North Korea.
Speaking at a news conference with French foreign minister Michel Barnier, Dr Rice urged North Korea to come back to the negotiating table.
Six-party talks aimed at ending the reclusive state's nuclear programme have been stalled for almost a year.