In an exclusive interview with TODAY's Matt Lauer, Caroline Kennedy, the former U.S. ambassador to Japan, said she's troubled by President Donald Trump's "America first" approach to foreign policy.

"To be taken for granted, or to be insulted as an ally who has fought alongside the United States for example, with Australia, or who contributes a huge amount to American security, in the case of Japan and Korea, is alarming and I think that, hopefully, the president will realize the benefits of working with our friends and allies around the region," Kennedy said.

Kennedy stepped down last month after serving three years as ambassador.

Earlier Friday, Defense Secretary Mattis arrived in Japan as part of his first foreign trip, a mission to reassure the nation that the United States will remain a strong ally despite tough rhetoric from its new president.

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Mattis headed to Japan after leaving South Korea, where the retired Marine Corps general tried to reassure leaders there of the same thing.

“The region is so critical to our future, so it’s important that the defense secretary went to consult and reassure our allies about our commitment,” she said.

"It’s important the defense secretary went to consult & reassure our allies about our commitment.” #CarolineKennedy on Mattis' trip to Japan pic.twitter.com/mebQYVwM1d — TODAY (@TODAYshow) February 3, 2017

During the election campaign, Trump pledged to force Japan and other Asian countries to pay more for their own defense.

Kennedy said Japan already contributes more than any other country.

"They contribute more than 75 percent of the cost of the bases, and it’s in our interest that Japan be strong and that our troops be there. That makes us safer here at home,” she said.

Kennedy said the United States also has an economic interest in keeping good relations with Japan, which she described as “our number one ally” in the region and one of the most strategic partners.

“Japan’s own security helps the United States be safer, and it provides a lot of jobs and a lot of economic opportunities for American companies,” she said.

Kennedy, who only recently returned home after years abroad, said "it's great to be home" but declined to say what her next steps might be.

"I'm looking to figure what I’ll do next," she said.

Asked if she would consider or rule out a run for public office, she joked "I think I'd rather be on morning TV."

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