TOKYO — Shinzo Abe’s visit to Iran this week, the first to that country by a Japanese prime minister in more than 40 years, is the latest in a series of high-minded but long-shot efforts to lift Japan’s influence on the global stage.
As he arrives in Tehran on Wednesday, Mr. Abe is putting himself directly in the middle of a confrontation between the United States and Iran that has raised fears of war.
The tensions, which began with President Trump’s decision to pull out of the 2015 nuclear accord and impose crippling sanctions, escalated recently as the Trump administration moved additional troops into the Persian Gulf after accusing Iran of plotting to attack American targets.
For Japanese business leaders, the conflict is a headache. Under American pressure, Japan has stopped oil imports from Iran, a country with which it has long enjoyed cordial relations. Japanese businesses, too, have reassessed their ties with the country for fear of provoking American displeasure.
For Mr. Abe, however, the crisis is an opportunity. In November, he is set to become the longest-serving prime minister in Japan’s history. But he is struggling to cement a lasting political legacy, and has tried to make a mark with diplomatic overtures to countries like North Korea and Russia.
The prime minister has also worked assiduously to cultivate a personal relationship with Mr. Trump, who has voiced support for Mr. Abe’s outreach to Iran, and who has said he himself is open to doing the same. During Mr. Abe’s 24-hour diplomatic sprint, he plans to meet with President Hassan Rouhani and Iran’s supreme leader, Ayatollah Ali Khamenei.
But the odds of any breakthrough are long, and Japanese officials have worked to lower expectations. Mr. Abe is not bearing a message from the American president, government officials told reporters on Tuesday. Nor is he seeking to serve as a mediator between the two countries, they said.
The chief cabinet secretary, Yoshihide Suga, said Mr. Abe would use the visit as an opportunity to encourage Iran’s leaders to “ease regional tensions.” And Mr. Abe, speaking at Haneda Airport in Tokyo before leaving for Iran, said he wanted Japan to “play whatever role it can to promote peace and stability in the region.”
The formulation seemed like a step down from the grander vision Mr. Abe described during meetings late last month with Mr. Trump in Tokyo, where the prime minister called for “close collaboration” between the United States and Japan to prevent tensions with Iran from turning into armed conflict.
But even the modest goal of lowering tensions might be a stretch. While Japan has good relations with both the United States and Iran, it has little ability to affect the outcome of the dispute between them, said Tobias Harris, an expert on Japanese politics at Teneo Intelligence, a consulting firm in Washington.
Japan has not clearly articulated what it hopes to achieve with Mr. Abe’s visit, Mr. Harris said, and even if it did, “Japan doesn’t have military power in the region.”
“It’s an important consumer but it is not a major market for Iranian goods,” he added. “What leverage does it have?”
In its favor is Japan’s long history of friendly relations with Iran, which is in large part a reflection of Tokyo’s desire for stability in the Middle East, a crucial supplier of energy to Japan. Mr. Abe has met with Mr. Rouhani at least six times since taking office, and the two countries are celebrating 90 years of diplomatic relations.
And Japan has tried to broker peace with Iran before. In 1984, Mr. Abe accompanied his father, who was then Japan’s foreign minister, on a failed mission to mediate the war between Iran and Iraq.
Japanese officials played up the countries’ relationship ahead of the visit, presenting Mr. Abe as a trusted interlocutor who can lend a sympathetic ear to Iran and convey its concerns to the rest of the world.
“We can’t play hardball,” said Kuni Miyake, a former Japanese diplomat who served in the Middle East. “We don’t want to. But as a soft power, we can do something different. Mr. Abe’s fully aware of that.”
While Iran appreciates Japan’s friendship, it is also wary of Tokyo’s close relationship with Washington, said Koichiro Tanaka, an expert on Iran at Keio University. He said that Tehran might require a peace offering from Mr. Abe in the form of a demonstration that he is willing to stand up to American sanctions.
Japan is also late to the game. Despite mounting concerns in the international community over the last decade about Iran’s behavior, Japanese officials chose not to participate in the negotiations that led to the 2015 deal to curb the country’s nuclear ambitions.
While that decision created space for Tokyo to pursue an independent policy toward Tehran, it has also limited Mr. Abe’s ability to play a role in resolving disputes over the deal.
Yukio Okamoto, a former Japanese diplomat and policy adviser to past Japanese prime ministers, said the world powers that sat at the table with Iran for all those years might be inclined to “sneer” at Mr. Abe’s efforts, asking “why should he step into what we’ve been toiling over, as a newcomer.”
Still, Mr. Abe has little to lose.
If anything, the trip could improve his standing at home as the country heads into elections for the upper house of Parliament next month. He wants to establish his legacy “by advancing Japan’s foreign and domestic agenda,” Mr. Okamoto said, and the Tehran visit offers an opportunity.
But while Mr. Abe has been an active advocate of Japan abroad, Mr. Okamoto added, he has “yet to show the public concrete solutions to several important issues, especially with Russia and North Korea.”
The Japanese leader has sought to insert himself in the dispute over North Korea’s nuclear program, offering to meet with the country’s leader with no preconditions. And he has aggressively courted the Russian president, Vladimir V. Putin, in an attempt to end a decades-old territorial dispute over islands in Japan’s north.
Those efforts have not yet yielded much success. North Korea has ignored his entreaties, and there has been no substantial movement in discussions with Russia. Mr. Abe’s courting of Mr. Trump, too, has produced limited benefits. It has delayed, but not eliminated, the threat of American tariffs against Japan’s key exports.
The prime minister has had more success with China. Last year, he became the first Japanese leader to visit the country since a 2012 disagreement over disputed islands derailed relations with Beijing.
Still, even if success is elusive, there’s no real downside to trying, said Daniel Sneider, an expert on Japanese diplomacy at Stanford University.
“I don’t see the French president going to Iran,” he said.
“If Abe goes, other people might follow,” he added. “And that makes it harder to trigger a conflict.”