U.S. President Donald Trump and Prime Minister Shinzo Abe before their talks at the White House on April 26. (Yuko Lanham)

Tokyo was baffled but kept calm after U.S. President Donald Trump's tweet and comments that seemed to negate mutual trust forged through his country's longtime defense pact with Japan.

Trump's June 24 tweet was in connection with June 13 attacks on tankers, including one owned by a Japanese company, in the Strait of Hormuz.

Trump tweeted: “China gets 91% of its Oil from the Straight, Japan 62%, & many other countries likewise. So why are we protecting the shipping lanes for other countries (many years) for zero compensation. All of these countries should be protecting their own ships on what has always been...."

A senior Foreign Ministry official expressed bewilderment about the president’s posting.

“I don't have any clues about the intention of the president’s tweet,” the official said.

Foreign Minister Taro Kono downplayed concerns at a June 25 news conference, saying, “I believe that his comment was not official.”

Defense Minister Takeshi Iwaya said the same day that, as of this moment, Japan does not plan to send Self-Defense Forces personnel to the strait to protect Japanese shipping.

“We will continue to expend all possible means to gather intelligence and closely watch how things will develop in the region,” he said at a news conference.

Echoing the defense minister’s comment, a high-ranking Defense Ministry official said the situation in the strait is not tense and does not warrant maritime security deployment under the Self-Defense Forces Law.

A day after the tanker incident, Iwaya made it clear that as the attacks were not threatening the survival of Japan the SDF should not use force for self-defense.

Trade minister Hiroshige Seko offered a similar perspective.

“At the moment, it does not jeopardize Japan’s stable energy supply,” he said June 25. “We, with heightened interest, will continue to watch how things will play out.”

The Japanese government also had to scramble June 25 to play down another surprise when Bloomberg News reported that Trump was contemplating pulling out of the Japan-U.S. Security Treaty.

Senior Foreign Ministry officials quickly denied the prospect of Washington withdrawing from the accord, which was signed in 1951 and revised in 1960.

Japan's defense policies place utmost priority on the alliance with the United States as the cornerstone of the country’s security.

Under the security treaty, the United States is obliged to defend Japan if it is attacked. In return, it is allowed to base military forces in Japan. But Japan is not required to come to the aid of the United States if it comes under attack.

U.S. critics of the arrangement have long argued that the pact is one-sided. Trump feels the same way, according to the Bloomberg report.

The Abe administration enacted a package of security legislation in 2015 to allow the SDF to significantly expand its activities overseas to help its allies.

After the Bloomberg report, Japanese government officials sounded out the U.S. side through diplomatic channels about the veracity of the report.

Kono told a news conference in the afternoon of June 25 that the White House had made clear it does not plan to withdraw from or review the bilateral security treaty as such a move would be in conflict with the U.S. government’s position.

Still, Trump has long demanded that U.S. allies in Asia and Europe should shoulder more of the cost of stationing U.S. forces, calling it an excessive burden on Washington.

Japanese government officials tasked to negotiate with their U.S. counterparts over Japan’s host nation support to the U.S. military in Japan have heightened a sense of caution following Trump's recent remarks.

The U.S. side is expected to step up its demand for Japan to pay more in talks that will likely start next year.

(This article was written by Ryo Kiyomiya and Ryuichi Yamashita.)