North Korea may be preparing a second nuclear test, Japan's foreign minister and media reports said on Tuesday, just days after the Stalinist regime was slapped with UN sanctions over its first trial.
Foreign Minister Taro Aso told reporters Japan had received information of possible preparations after US spy satellites reportedly picked up suspicious movements of trucks and people near the site of the October 9 blast.
"I have received information on that, but can't disclose the details," Aso said. He did not elaborate further, and other officials cautioned that there was no hard evidence to back up the reports.
Nevertheless, the alert underlined global jitters over Pyongyang's nuclear activities and emerged as the United States confirmed the October 9 test was a nuclear detonation as North Korea had claimed, although relatively small at less than one kiloton.
That test brought global condemnation upon Kim Jong-II's regime, including from its closest ally China, and triggered a unanimous UN Security Council resolution imposing sanctions on the reclusive nation.
As the United States launched a diplomatic drive to shore up the sanctions, President George W Bush said Kim "is going to have some choices to make."
"I am deeply concerned about the starvation inside of North Korea. I am worried about concentration camps inside of North Korea. I am worried about the human condition inside North Korea," he told Fox News television.
"And we are now making it clear—not just the United States—but other nations are making it very clear to North Korea that there is a better way forward. And so, we'll be able to judge his intentions and his motives as time goes on."
Bush also said he was confident China would enforce the sanctions, despite Beijing's concerns that aggressive inspection of cargo to and from North Korea could provoke the regime.
Earlier, the US intelligence establishment said air samples had confirmed the October 9 blast was nuclear but with an unusually low yield of less than one kiloton, indicating the detonation may have partially failed.
A US intelligence official said new activity detected at suspected North Korean test sites "doesn't necessarily lead one in the direction of another test."
He told on condition of anonymity that while no one could rule out the possibility of a second test, "there isn't any evidence one is imminent."
A government official in Seoul said South Korea was also aware of the signs but cautioned they could be part of unrelated military activities.
US Secretary of State Condoleezza Rice said she would call on Japan, South Korea, China and Russia during visits later this week to "share the burdens as well as the benefits" of reining in Pyongyang.
The UN resolution bans trade with North Korea related to dangerous weapons, calls for a freeze on financial assets and imposes a travel ban on those tied to the country's nuclear and other weapons of mass destruction programmes.
The most contested measure is the call for cargo inspections, designed to prevent the impoverished state selling nuclear material to terrorists or rogue states.
Rice said her talks in the various Asian capitals and Moscow would include detailed discussions of "mechanisms" for the searches without "ratcheting up" tensions.
Christopher Hill, the US pointman on North Korea, flew to Seoul from Tokyo to lay the groundwork for Rice's visit, which will include talks on Thursday with her Japanese and South Korean counterparts.
Also in Seoul was Russian Prime Minister Mikhail Fradkov, who was due to meet his South Korean opposite number Roh Moo-Hyun on Tuesday.
Russia is one of the six nations—along with the two Koreas, China, Japan and the United States—involved in talks trying to persuade Pyongyang to abandon its nuclear weapons programme.
The North, which says it needs nuclear weapons to defend itself against a possible US attack, insisted in a speech on Monday by the regime's number two, Kim Yong-Nam, that it was "seriously threatened" and urged its citizens to brace for "final victory."