TOKYO - Japanese Prime Minister Shigeru Ishiba said on Wednesday that other nations do not decide its defense budget after US President Donald Trump's nominee for a top Pentagon policy role called for Tokyo to increase its spending.

"Japan decides its defense budget by itself," Ishiba told parliament. "It should not be decided based on what other nations tell it to do."

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In 2022, Japan announced a 43 trillion yen ($287.09 billion) military build-up strategy over five years, doubling its defense budget to about 2 percent of the country's gross domestic product.

Elbridge Colby, the Trump administration's nominee to become under secretary of defense for policy, said Japan should increase its spending.

"Japan should be spending at least 3 percent of GDP on defense as soon as possible and accelerating the revamp of its military to focus on a denial defense of its own archipelago and collective defense in its region," Colby said in a written response to advance policy questions from US senators.

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Japan's top government spokesperson said the nation's defense buildup prioritizes quality over the size of its budget.

"What we think important is the substance of defense capabilities, not the volume or GDP ratio," Chief Cabinet Secretary Yoshimasa Hayashi told a regular press conference.

Colby admonished Japan for acting too slowly to raise defense spending.