Meanwhile, a long-simmering scandal reared its head again on Monday, when Japan’s Finance Ministry released a report showing that officials had tampered with crucial documents related to a suspicious sweetheart land deal that may implicate Mr. Abe.
“That’s a pretty deadly combination,” said Daniel C. Sneider, a lecturer in East Asian studies at Stanford University. “I can’t imagine that he hasn’t had a few troubled moments since then.”
For now, Mr. Abe is likely to be most preoccupied with trying to save his political career. On Tuesday, the Japanese news media reported that a Finance Ministry employee in a regional branch who had committed suicide left a memo saying that his office had been ordered to alter documents under direct instructions from headquarters.
Farther afield, analysts said Mr. Abe was probably disappointed that the close relationship he had worked so hard to build with Mr. Trump — cultivated over rounds of golf — had not kept him on the inside track.
Immediately after learning of Mr. Trump’s plans, Mr. Abe announced he would visit the president next month.
“You feel compelled immediately upon the news about the meetings with the North Koreans to go rush off to Washington in order to reassure yourself? That’s interesting,” Mr. Sneider said. “It means that it’s a kind of relationship that requires that kind of constant shoring up personally.”
On Tuesday, Mr. Abe kept short his public remarks about the briefing with the South Korean envoy, reiterating Japan’s desire to curtail the North’s nuclear and ballistic program as well as seek the return of Japanese citizens abducted by North Korea in the 1970s and ’80s.
Underscoring Japan’s continued hard-line stance, Mr. Abe said he wanted North Korea to take “specific actions toward denuclearization,” although he did not say what those steps would look like. North Korea has already fired ballistic missiles over Japan, which could be at the front lines of any conflict.
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But just as the South Koreans spoke for Mr. Trump and Mr. Kim last Friday in Washington, Mr. Suh, addressing Japanese reporters in Tokyo, said Mr. Abe had “expressed his respect to President Moon’s leadership to improve relations between South and North Korea and maintain peace toward denuclearization on the Korean Peninsula.”
South Korea’s presidential palace, known as the Blue House, also issued a statement in which it quoted Mr. Abe saying that he did not believe North Korea would use the talks “simply to buy more time.”
A spokesman from Japan’s Foreign Ministry declined to confirm that Mr. Abe had made either of the remarks during his meeting Tuesday with the South Korean envoy.
For Japan, there are risks to Mr. Trump’s speaking independently to Mr. Kim without consulting it or South Korea.
“North Korea has been playing a game of saying one thing and later on saying, ‘Oh, what we really meant by this was this and that,’” said Narushige Michishita, director of the Security and International Studies Program at the National Graduate Institute for Policy Studies in Tokyo. So, for example, North Korea could agree to stop tests of strategic ballistic missiles but then claim such language did not cover shorter range missiles that could target Japan or South Korea, Mr. Michishita said.
Mr. Abe’s supporters said he might yet restore his rapport with Mr. Trump, which could also help him domestically.
“The Japanese people know Abe has close ties with President Trump,” said Yoichi Takahashi, a former Finance Ministry official and professor at Kaetsu University in Tokyo. “People believe Japan should not be isolated from the U.S.-North Korea deal, and they know Abe is the best politician and no one else can be as active as Abe.”
Other analysts said better communication with Mr. Abe was no guarantee that Mr. Trump would not act impulsively or make damaging concessions in a meeting with Mr. Kim.
“My own concern is the way this summit meeting was granted to North Korea,” said Fumiaki Kubo, a professor of political science at the University of Tokyo. “This itself was a huge concession.”
Mr. Kubo added that Mr. Abe “might be able to persuade Mr. Trump” to stick to a firm plan for denuclearization, “but Mr. Trump might forget what he was told or instructed or advised.”
For now, analysts said, Mr. Abe will have to remain pragmatic. “Abe’s advisers understand that Japan is not the major player on the North Korean issue,” said Tsuneo Watanabe, a senior research fellow at the Sasakawa Peace Foundation in Tokyo. “So I think they are not so optimistic that their voice is going to be reflected in the current situation.”
And with Mr. Trump susceptible to changing his mind, “a strong policy position is not so helpful,” Mr. Watanabe said. “Japan needs to be flexible.”