PANMUNJOM, Korea (AP) — The Latest on U.S. Defense Secretary Jim Mattis in Asia (all times local):

12:30 p.m.

U.S. Defense Secretary Jim Mattis is accusing North Korea of building a nuclear arsenal to "threaten others with catastrophe," and says the Trump administration remains committed to compelling the North to accept complete nuclear disarmament.

Mattis pledged solidarity with the South in remarks while inside the Demilitarized Zone that separates the two Koreas. He said the U.S. stands "shoulder to shoulder" with the Korean people in confronting the threats posed by the regime of Kim Jong Un.

Mattis is in South Korea to meet with the nation's top defense officials and American military commanders on the front line in countering North Korea's nuclear weapons program.

While emphasizing a diplomatic solution, Mattis has said the U.S. is prepared to take military action if the North doesn't halt its development of missiles that could strike the mainland United States.

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11 a.m.

U.S. Defense Secretary Jim Mattis is making a show of solidarity with South Korea by traveling to the heavily fortified buffer zone between North and South, known as the demilitarized zone or DMZ.

Mattis is also visiting a U.S.-South Korean military observation post to peer into the North and get briefed on conditions along the border. The two countries have been separated by the border since a truce halted the Korean War in 1953.

Mattis is in South Korea to meet with the nation's top defense officials and American military commanders on the front line in countering North Korea's nuclear weapons program.

Mattis is emphasizing the Trump administration's push for a diplomatic solution. But he's also said the U.S. is prepared to take military action if the North doesn't halt its development of missiles that could strike the mainland United States.

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9:20 a.m.

Pentagon chief Jim Mattis is in South Korea to meet with the nation's top defense officials and American military commanders on the front line in countering North Korea's nuclear weapons program.

Mattis is emphasizing the Trump administration's push for a diplomatic solution. But he's also said the U.S. is prepared to take military action if the North doesn't halt its development of missiles that could strike the mainland United States.

On Thursday the Trump administration imposed sanctions on 10 North Korean officials and organizations over human rights abuses and censorship. And a U.S. official tells The Associated Press that a rare military exercise involving three of the U.S. Navy's aircraft carrier strike groups is being planned for next month in the Asia Pacific.

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6:16 a.m.

The American defense secretary has arrived in South Korea to consult with his counterpart and U.S. military commanders on countering North Korea's nuclear weapons program.

Jim Mattis is emphasizing the Trump administration's push for a diplomatic solution to the problem. But he also has warned that the U.S. is prepared to take military action if North Korea does not change course.

He will be meeting on Saturday with South Korean officials as part of an annual consultation on defense issues on the Korean peninsula.

Mattis is being joined in Seoul by the chairman of the U.S. Joint Chiefs of Staff, Gen. Joseph Dunford.

President Donald Trump is scheduled to visit Seoul in November.