South Korean Foreign Minister Ban Ki-moon left for Tokyo yesterday to discuss strategies with Japanese leaders ahead of six-nation talks on North Korea's nuclear program.
Two senior US officials were also set to arrive in the Japanese capital yesterday for separate talks on the issue.
Ban, also the new UN secretary-general, was scheduled to meet his Japanese counterpart, Taro Aso, yesterday evening, Japan's Foreign Ministry said.
He was expected to meet Japanese Prime Minister Shinzo Abe today.
Meanwhile, Robert Joseph, US undersecretary of state for arms control and international security, and Nicholas Burns, undersecretary of state for political affairs, were also due to arrive in Tokyo yesterday, Japan's Foreign Ministry said.
Officials from the three allied nations were expected to talk about coordinating UN Security Council sanctions imposed on North Korea, and to discuss a strategy for handling the volatile communist state at renewed talks expected later this year.
The three countries also plan to hold a meeting of their chief nuclear negotiators in Washington as early as this weekend to discuss strategies to move the nuclear talks ahead, Yonhap news agency reported, citing government officials.
North Korea agreed last week to return to the six-country disarmament negotiations -- which also include China, Russia, the US and South Korea -- in the first easing of tension since the North's underground nuclear test last month.
Pyongyang said it would return to the talks to seek an end to a US-led campaign blocking its access to international banks because of alleged illegal activity, such as counterfeiting and money laundering.
Washington had said it would discuss the financial restrictions only in the context of the six-nation talks.
But even as it agreed to return to talks, the North kept up its usual harsh rhetoric on Saturday.
It denounced US leaders as "warmongers" and called Japanese officials "political imbeciles" for saying that they would not accept Pyongyang as a nuclear power.
The North also repeated its demand that Japan stay away from the six-party talks "because it is no more than a state of the US."
In a statement carried by the official Korea Central News Agency (KCNA), North Korea's Foreign Ministry said most of the international community had welcomed Pyongyang's return to the talks.
"Only Japan ... expressed its wicked intention," said the statement, referring to Tokyo's stance that it would not accept a nuclear North Korea. "The Japanese authorities have thus clearly proved ... that they are political imbeciles," it said.
Pyongyang attacked Washington in an editorial by the typically bellicose Rodong Sinmun newspaper, condemning the US as "fanatic warmongers who destroy peace and security on the Korean peninsula."
"The US has become more fanatic in pushing for its war scheme to attack the North, taking issue with our war-deterrent measures. We were compelled to strengthen to protect our sovereignty and right to survive from their serious threat," the editorial said.
The North often refers to its nuclear program as a self-defensive measure against the threat of a US attack. Washington has repeatedly insisted it has no intention of attacking.
North Korea's latest remarks came after its deputy leader said that progress at the revived talks on the nation's nuclear program would depend on the US' "attitude."