Japan is looking at intensifying diplomacy at the top level now that a historic U.S.-North Korea summit is set for June 12 and possibly more such meetings may come.

Information gathering and policy coordination are critical yet apparently difficult as things are often unpredictable under U.S. President Donald Trump, political experts say.

Trump's recent about-face on holding a summit with North Korean leader Kim Jong Un and his recent rhetoric that he does not want to use the term "maximum pressure" on Pyongyang have left Japanese officials wondering what his game plan is.

Trump and Abe ride a golfcart in Florida on April 18 [Photo courtesy of Japan's Cabinet Public Relations Office]

Prime Minister Shinzo Abe is travelling this week to Washington to get a better understanding of Trump's thinking and to reaffirm the importance of a joint approach to North Korea.

The envisaged visit will be his second in roughly two months, and, with Japan calling for North Korea's complete, verifiable, and irreversible denuclearization, highlighting the urgency of policy coordination until the last minute.

"It's in the hands of the president, so the prime minister himself needs to go and talk," one government official said.

A recent spate of fast-moving developments has sent political pundits scrambling to interpret what Trump's intentions are.

After meeting with a senior North Korean official on Friday, Trump tried to play down expectations for the June 12 summit, describing it as the start of a "process" with more than one meeting needed.

Takashi Kawakami, a professor well-versed in Japan-U.S. relations at Takushoku University, said Trump has come to understand the complexities of the situation surrounding North Korea's denuclearization.

"The biggest concern for Japan would be that a vague agreement that falls short of CVID will be reached," Kawakami said, using an abbreviation for the "complete, verifiable and irreversible denuclearization" of North Korea.

"Japan will have to make its case for complete denuclearization to lay the groundwork for resolving the issue of North Korea's past abductions, which is at the heart of the Abe administration," he added.

With the United States moving toward dialogue and South Korea warming to North Korea with which it is technically at war, some critics argue Japan is out of the loop.

But Tetsuo Kotani, senior fellow at the Japan Institute of International Affairs, dismisses such a view. Tokyo, he said, is "cautiously pessimistic" and will likely consider how to approach North Korea depending on the outcome of the Trump-Kim meeting.

"Maybe we are sitting in the backseat," Kotani added. "But I think because of this close U.S.-Japan coordination and close relationship between Mr. Abe and Mr. Trump, Japan is not actually left out (of the process)."

After dozens of telephone conversations and a series of face-to-face meetings, the two leaders have built a rapport. But that did not exempt Japan, a long-time security ally, from being subject to higher steel and aluminum tariffs imposed by the Trump administration to defend national security.

Trump's change in rhetoric on North Korea has also left Japan uneasy. Despite that, Yoshihide Suga, the top government spokesman, said Japan and the United States have coordinated closely on policy and that there is no change in urging Pyongyang to take concrete actions.

Japan has maintained that the resolution of the abduction, missile and nuclear issues is essential before it can normalize ties with North Korea.

With roughly a week to go until the Singapore summit, Abe has expressed hope for the success of the meeting.

The summit initiative was mediated by South Korea, which agreed with North Korea in late April to pursue "complete denuclearization" of the Korean Peninsula.

Lee Su Hoon, South Korea's ambassador to Japan, recently said North Korea may also wish to acquire a regional "strategic" balance that includes Japan.

"It would be beneficial for Prime Minister Abe to talk with North Korea as soon as possible," Lee said at a forum. "In my thinking, the chances of success are good.