Pentagon chief Mattis arrives in S. Korea amid US President's uncertainty
It is the first overseas tour by a senior official in the Trump administration as concerns rise about the direction of American policy.
It is the first overseas tour by a senior official in the Trump administration as concerns rise about the direction of American policy in the region under the protectionist and fiery US leader.
On the campaign trail, Trump threatened to withdraw US forces from the two countries if they do not step up their financial support. Some 28,500 US troops are based in South Korea and 47,000 in Japan.
The rhetoric has raised concerns in both Seoul and Tokyo, and in a statement this week South Korea's defence ministry said it hoped Mattis' trip would be "an opportunity for the Trump administration to maintain and strengthen US commitment" to their alliance.
Seoul also hopes the new Pentagon chief will reaffirm America's commitment to defend it in the face of growing threats from nuclear-armed North Korea.
The North's leader Kim Jong-Un boasted last month that the country was in the "final stages" of developing an intercontinental ballistic missile.
The two allies last year announced the deployment of the Terminal High Altitude Area Defense (THAAD) system following a series of atomic and missile tests, infuriating China which fears it will undermine its own ballistic capabilities.
Mattis is due to meet with South Korea's acting president Hwang Kyo-Ahn Thursday and hold talks with Defense Minister Han Min-Koo Friday, before heading to Japan.
In Tokyo he will meet with Defense Minister Tomomi Inada and other officials, the Pentagon said.
Japanese Prime Minister Shinzo Abe -- who is scheduled to meet Trump next week in Washington -- told lawmakers he intends to press Mattis about "the significance of the Japan-US alliance."
Mattis' Asia tour comes as relations between the US and other world powers such as Mexico and Australia get off to a rocky start.
The Washington Post reported late Wednesday that Trump ripped into his Australian counterpart Malcolm Turnbull during a call last week, with the president apparently fuming at a refugee accord he called "dumb" and cutting the call short.
Australia is considered a close US ally in Asia Pacific, and one of the so-called "Five Eyes" with which the US routinely shares sensitive intelligence.
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