Hillary Clinton: "The US-Japanese alliance is vitally important"
Hillary Clinton has arrived in Japan on her first overseas visit as the top US diplomat, days after pledging greater engagement with Asia.
Landing in Tokyo, the US secretary of state said America's ties with the region were "indispensable" to addressing global challenges.
Mrs Clinton will also visit Indonesia, South Korea and China in coming days.
Talks will focus on the economic crisis and on North Korea, amid speculation it is to test-fire a long-range missile.
Hours before Mrs Clinton arrived in the region, North Korea hit out at the reports - but said it was entitled to pursue peaceful scientific research and "space development".
Mrs Clinton said she expected North Korea to stick to the aid-for-disarmament deal it agreed in February 2007.
"The North Koreans have already agreed to dismantling," she told the Associated Press news agency as she travelled to Japan. "We expect them to fulfil the obligations that they entered into."
This is the first time Asia has been the initial trip for a US secretary of state since the 1960s.
By making Japan her first stop, Mrs Clinton is seeking to reassure America's key ally in the region that its relationship with Washington is still strong and will remain so, says the BBC's state department correspondent, Kim Ghattas.
There has been fear in Tokyo that the Obama administration would neglect Japan as it focuses on more pressing issues, our correspondent says.
Mrs Clinton is to hold talks with top leaders on Tuesday and sign a deal relocating US troops from Okinawa to Guam.
Japan's top government spokesman, Takeo Kawamura, said the two sides would discuss ways of strengthening both the Japan-US alliance and co-operation on the issue of North Korea.
Mrs Clinton is also scheduled to meet the families of Japanese nationals abducted by North Korea in the 1970s and 1980s.
The US secretary of state will then move on to Jakarta, followed by Seoul. But her final stop, Beijing, will be at the heart of the tour, our correspondent adds.
When she was running for president last year, Mrs Clinton wrote an article outlining her foreign policy in which she stated that America's relationship with China would be the most important bilateral relationship in the world this century.
Speaking to the BBC on Friday, Mrs Clinton said there were real opportunities to develop a good relationship with Beijing on issues such as climate change and clean energy.
And in a speech the same day, she said Asian links were a priority.
"I hope to signal that we need strong partners across the Pacific, just as we need strong partners across the Atlantic," she told the Asia Society in New York.
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