The United States asked Japan earlier this year to pay significantly more -- about five times as much per year -- to support U.S. forces based on the soil of its major Asian ally, government sources said Saturday.

The request was delivered by John Bolton, then national security adviser to U.S. President Donald Trump, when he visited Japan in July for talks with top officials, including then Foreign Minister Taro Kono and then Defense Minister Takeshi Iwaya, the Japanese sources said, adding that Tokyo rejected the request.

In Japan's fiscal 2019 draft budget, about 197.4 billion yen ($1.8 billion) has been earmarked to host U.S. forces, while Trump has criticized obligations under the decades-old security treaty between the two countries as being unfair.

Japan would have to pay more than 980 billion yen annually if it had accepted the request.

Bolton told the Japanese officials that the United States wanted to discuss frankly with Japan about the future of the cost sharing, and that it would also ask South Korea, another key U.S. ally in Asia, for a fivefold increase in its payment, the sources said.

The officials told Bolton the fivefold hike is "unrealistic," arguing Japan has already been shouldering the highest share of stationing cost among U.S. allies, one of the sources said.

According to a U.S. Defense Department report in 2004, Japan's share of the overall expenses for U.S. forces in the country stood at 74.5 percent in 2002, compared with South Korea's 40 percent and Germany's 32.6 percent.

Since then, the United States has not revealed changes in the ratio.

A Japanese Defense Ministry source said, "(The request) must be part of a 'deal' President Trump likes to make. I think he wanted to see the reaction of Japan."

The Japan-U.S. agreement on the cost sharing over the five-year period through fiscal 2020 will expire at the end of March 2021, and new negotiations on Tokyo's so-called host-nation support are expected to be in full swing possibly next spring.

The U.S. magazine Foreign Policy reported Friday that the Trump administration has asked Tokyo to quadruple its payment to around $8 billion to cover expenditures for maintaining the forces in Japan.

Under the bilateral security treaty, about 50,000 U.S. troops are stationed in Japan, providing the major U.S. forward logistics base in the Asia-Pacific region. The southern island prefecture of Okinawa hosts the bulk of the U.S. military facilities in Japan.

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