Visiting Tehran today, Qatar’s emir aspires to revive his country’s role as a regional mediator and to facilitate President Biden’s aim of renewing the Iran nuclear deal. 

“Regarding the negotiations taking place in Vienna, Qatar always looks at them positively,” the emir, Tamim bin Hamad al-Thani, said during a news conference alongside Iran’s president.

“The only solution to any disagreement is by peaceful means and dialogue,” Mr. al-Thani added, “God willing, we are pushing all the parties” to reach a “fair” agreement. 

The Vienna talks, which have included America negotiating through European and Russian mediators after Iran refused face-to-face talks, broke off in March. One contested issue was Tehran’s demand to remove the Islamic Revolutionary Guard Corps from America’s list of foreign terror organizations. 

Nearly a decade ago the tiny sultanate of Oman facilitated secret talks between President Obama and Iran, leading eventually to the conclusion of the 2015 Joint Comprehensive Plan of Action.

Now, “the Qataris are positioning themselves to be the Oman of this round,” the Foundation for Defense of Democracies’s Iran watcher, Behnam Ben Taleblu, says. Doha, he added, hopes to “midwife a new flawed deal and ensure that Iran gets a lot of cash.” 

Both Iran’s president, Ebrahim Raisi, and the supreme leader, Ali Kamenei, whom Mr. Al-Thani also met, declined to address the nuclear deal. Instead, as the state-owned IRNA reported, the leaders discussed “unfreezing Iran’s assets, cooperation in holding the 2022 World Cup, pursuing prisoner exchanges, and cooperation in the field of energy.”

As part of President Trump’s “maximum pressure” policy, which in 2018 replaced Mr. Obama’s Iran rapprochement, America froze international proceeds from Iranian oil sales. Tehran’s attempt to get back those assets before a nuclear deal is agreed upon has become a contentious point in the Vienna talks. 

Qatar’s Al Ubaid airfield is America’s largest military air base in the Mideast. To highlight the alliance with Doha, Mr. Biden hosted the emir at the White House in January. At the same time, Qatar’s most profitable gas field is situated at a border area and is shared with Iran. Qatar also conducts extensive trade with the Islamic Republic. 

Relations with both countries place Qatar in a perfect position to become an interlocutor. Yet, an Iranian decision in January to display IRGC missiles at a Doha international maritime defense expo proved too awkward for Washington. 

“We reject the presence of Iran at a maritime defense exhibit, considering that it’s Iran that single-handedly is threatening maritime stability throughout the Gulf region,” the State Department spokesman, Ned Price, said at the time. 

Through the years, however, Qatar has honed the art of navigating a Mideastern maze of alliances and enmities. Last year saw a blockade imposed on the country by the Saudi-led Gulf Cooperation Council effectively ended, and earlier this month the emir hosted the GCC’s secretary-general, Nayef al-Hajraf, at Doha.

While tensions with the Saudis, the Emiratis, and other GCC members have not completely dissipated, trade has been renewed after being frozen in 2016. 

Similarly, while Qatar is a major Hamas backer, it has also long maintained unofficial ties with Jerusalem. Doha often relays messages between Israel and Hamas, and has facilitated ceasefires by delivering cash to Gaza. 

In Tehran, though, Mr. Khamenei urged Qatar to further support Palestinians against Israel. Yesterday Doha’s tallest building displayed a portrait of an Al Jazeera reporter, Shireen Abu Akleh, who was killed while covering armed clashes at Jenin in the West Bank.

The Qatari-owned Al Jazeera has become a source of contention between Doha and fellow Arab regimes that the network often criticizes. As the most-watched Arab-language television outlet, Al Jazeera has made tiny Qatar a major influencer and given it an oversize role in shaping Mideast politics. 

Back in the swing of things now, Mr. al-Thani plans to follow his Iran trip with a visit to Turkey, a fellow Sunni powerhouse trying to make peace with its neighbors. From there, he will travel to several European capitals.

As the world’s second-largest exporter of liquified gas — which it currently mostly sends to Asia — Qatar now aims to replace sanction-suffering Russia as a major energy supplier to Europe. Iran, which shares gas fields with Qatar, also wants to resume oil deliveries to Europe.

America and European countries are hoping, wrongly perhaps, that such deals would ease inflation and other global economic woes. 

In return, Iran can help Qatar, the host of this year’s World Cup, to overcome its hotel room shortage. Tehran has reportedly offered to host soccer enthusiasts from the world over at its Kish island near Qatar. 

It should be noted, though, that Paris today identified a French couple as the Europeans Iran arrested yesterday on what appear to be trumped-up charges. Soccer fans should be aware of the Islamic Republic’s hostage diplomacy: Following stays at a Kish hotel they, too, could end up extending their Mideast vacations with stints at Iran’s notorious Evin prison.