By Jon Gambrell and Mari Yamaguchi

The Associated Press

Japanese Prime Minister Shinzo Abe’s trip to Tehran represents the highest-level effort yet to de-escalate tensions between the U.S. and Iran as the country appears poised to break the 2015 nuclear deal it struck with world powers that America earlier abandoned.

While Abe’s trip to Iran marks the first visit of a sitting Japanese premier in the 40 years since the Islamic Revolution, it remains unclear if he’ll end up going home with any success.

Iran is threatening to resume enriching uranium closer to weapons-grade level on July 7 if European allies fail to offer it new terms. While President Donald Trump says he wants to talk to Tehran, the U.S. has piled on sanctions that have seen Iran’s currency plummet along with its oil exports.

The U.S. also has sent an aircraft carrier and B-52 bombers to the region, along with hundreds more troops to back up the tens of thousands already deployed across the Middle East. The U.S. blames Iran for a mysterious attack on oil tankers off the coast of the United Arab Emirates, while Iranian-­backed rebels in Yemen continue to launch coordinated drone attacks on Saudi Arabia.

The stakes, analysts say, couldn’t be higher.

“Just going to Iran doesn’t resolve any problem,” said Kazuo Takahashi, an Open University of Japan professor of international politics and expert on the Middle East. “He would have to help open a path of dialogue between the U.S. and Iran, and that could be a major risk.”

Iran’s nuclear deal, agreed to by China, Russia, France, Germany, the United Kingdom and the U.S., saw Tehran agree to limit its enrichment of uranium exchange for the lifting of crippling sanctions. Iran long has insisted its program was for peaceful purposes.

In withdrawing from the deal last year, Trump pointed to the accord not limiting Iran’s ballistic missile program and not addressing what American officials describe as Tehran’s malign influence across the wider Mideast. Those who struck the deal at the time described it as a building block toward further negotiations with Iran, whose Islamic government has had a tense relationship with America since the 1979 takeover of the U.S. Embassy in Tehran.

Trump spoke Tuesday with Abe, said Yoshihide Suga, Japan’s chief Cabinet secretary. Abe also in recent days has spoken with Israeli Prime Minister Benjamin Netanyahu, Saudi Crown Prince Mohammed bin Salman and Abu Dhabi’s Crown Prince Sheikh Mohammed bin Zayed Al Nahyan, all of whom are fierce critics of Iran.

Middle East peace is a must for Japan, which gets most of the oil fueling its economy from there. Japan had once purchased Iranian oil, but it has now stopped because of American sanctions.