Photo/IllutrationU.S. President Donald Trump and Prime Minister Shinzo Abe hold a joint news conference in Tokyo in November 2017. (Asahi Shimbun file photo)

The U.S. president trumpeted during a March 9 phone call with Prime Minister Shinzo Abe that he had "good news."

It was anything but.

The U.S. leader's announcement of a planned historic summit meeting by the end of May with North Korean leader Kim Jong Un caught Japan off-guard and dismayed as Tokyo had stood shoulder-to-shoulder with Washington on maintaining maximum pressure on Pyongyang to rein in its military provocations.

"It never occurred to us that such a decision would be made at this time," said a high-ranking Foreign Ministry official, describing the shockwaves reverberating in Tokyo.

The sudden shift in direction by Donald Trump--from belligerent taunts to dialogue--triggered concern in Japan that it could be kept away from the table on negotiations on the denuclearization of North Korea.

During the phone call with Trump, Abe proposed visiting the United States in early April to discuss the North Korea issue.

Although he was reeling from the ace card played by Trump, Abe went on to tell reporters that the two countries were 100 percent together on the issue.

Japanese government officials shared the concern of their U.S. counterparts that "dialogue for dialogue's sake was meaningless."

While Abe administration officials felt that dialogue between the United States and North Korea would eventually have to happen, based on their take of Washington's end goal, they never expected direct talks would be in the cards without first consulting Tokyo.

Japan had argued that North Korea must take specific steps, such as allowing inspections by the International Atomic Energy Agency, before any dialogue or negotiations could be held.

Many officials painted a bleak picture of what the sudden change in direction by Trump meant.

"The decision was made totally over Japan's head," said a former defense minister. "Japan has been left out of the picture."

While dialogue between the United States and North Korea is welcome if it leads to an avoidance of a military confrontation, Japan fears being left as the odd man out because it has been among the most vocal proponents of the highest levels of pressure on Pyongyang.

Abe himself cited the "national threat" emanating from North Korea as one of the reasons for calling a snap Lower House election last October.

The Abe administration's national security policy could also be called into question by the abrupt change orchestrated by Trump. For one thing, the planned deployment of the Aegis Ashore land-based missile defense system was primarily designed to respond to the military threat from North Korea.

There are other potential concerns looming for Japan, given a high-ranking Defense Ministry official's view that "It is inconceivable North Korea would ever abandon any nuclear weapons it got its hands on."

For Japan, another key concern is that Washington and Pyongyang may reach an agreement on intercontinental ballistic missiles but not include North Korea's other ballistic projectiles that clearly have Japan within range.

For those reasons, Abe is expected to make a pitch to Trump during their next meeting to not move too quickly toward a more conciliatory tone with North Korea.

But, as the latest decision shows, it will never be easy to predict what effect any advice or warning will have on the U.S. president.

(This article was written by Nozomi Matsui and Koji Sonoda.)