TOKYO (Kyodo) -- Japan on Wednesday pushed back against the demand by U.S. President Donald Trump's nominee for a top Pentagon policy post to boost its defense spending to 3 percent of its gross domestic product to tackle growing security challenges.

Prime Minister Shigeru Ishiba said Japan "determines its own defense spending, not at the direction of any other country," while Chief Cabinet Secretary Yoshimasa Hayashi emphasized the importance of the substance of capabilities over the budget amount.

The remarks came after Elbridge Colby, tapped to be undersecretary of defense for policy, said in a written statement at a Senate confirmation hearing on Tuesday, "Japan should be spending at least 3 percent of GDP on defense as soon as possible."

The Japanese government had long capped its defense spending at about 1 percent of GDP, or around 5 trillion yen ($33.5 billion), but has raised the budget in recent years with a goal of reaching 2 percent of national output by fiscal 2027.

Colby, meanwhile, said, "It makes little sense for Japan, which is directly threatened by China and North Korea, to spend only 2 percent," referring to Trump's calls for Taiwan and NATO members to allocate 10 percent and 5 percent of GDP, respectively.

The seasoned security expert, known as a China hawk, made the same claim about Japan's defense budget in a social media post before Trump won the presidential election in November to secure his non-consecutive second term from Jan. 20.