TEHRAN – The European Union’s coordinator of the talks in Vienna over reviving the 2015 Iran nuclear deal was briefly detained by the German police at the Frankfurt airport on his way back from Tehran to Brussels.

Enrique Mora revealed the incident on Twitter. “Retained by the German police at the Frankfurt airport on my way to Brussels, back from Tehran. Not a single explanation. An EU official on an official mission holding a Spanish diplomatic passport. Took out my passport and my phones,” he tweeted.

Mora appeared to have been detained for an hour as he tweeted an hour later that he was released. “Now released along with my two colleagues, the EU Ambassador to UN Vienna and the head of the EEAS Iran task force. We were kept separated. Refusal to give any explanation for what seems a violent of the Vienna Convention,” he said.

In Tehran, Mora met with Iran’s chief nuclear negotiator, Ali Bagheri Kani. After Mora’s visit, EU foreign policy chief Josep Borrell said the talks in Vienna have been “reopened.”

“Travelling again to Tehran for meetings with Bagheri Kani and other officials on the Vienna talks and other issues. Work on closing the remaining gaps of this negotiation continues,” Mora said on Twitter before heading to Tehran.

Mora’s visit comes as the EU foreign policy chief, Josep Borrell, is pushing for resuming the Vienna talks over reviving the 2015 Iran nuclear deal, officially known as the Joint Comprehensive Plan of Action (JCPOA), as soon as possible.

Borrell said the current stalemate cannot continue. “We cannot continue like this forever,” the EU chief diplomat said.

In a bid to get the talks going again, the EU foreign policy chief said he was dispatching Mora to Tehran in what he described as a “last bullet” push. In remarks to the Financial Times, Borrell said he is pushing for a “middle way” on the U.S. designation of the Islamic Revolution Guards Corps (IRGC) as a foreign terrorist organization.

Meanwhile, an Iranian official told Al Jazeera that more than 90% of the nuclear issues were verbally agreed upon, but that did not turn into a written agreement.

“Executive guarantees are the most important outstanding differences with Washington in the nuclear negotiation,” the official said, noting, “There are 6 issues that form the core of the main differences with America in the nuclear negotiations.”

The official said achieving agreement in the Vienna nuclear negotiations depends on America's seriousness and goodwill.

In the last round of the Vienna talks which was concluded nearly two months ago, Iran demanded that the United States remove the IRGC from its terrorist list, among other things. The U.S. refused the Iranian demands and the talks ground to a halt.

Borrell said the EU is going to strive for a middle ground on the IRGC designation. Borrell is considering a scenario whereby the designation on the guards is lifted, but kept in place on other parts of the organization, according to the Financial Times.

Mohammad Marandi, an academic close to the Iranian negotiating team, explained in a press interview published in conjunction with the visit of the European nuclear talks coordinator to Tehran that the main reason for the suspension of negotiations is America's failure to provide “sufficient guarantees” regarding its commitment to implement its obligations stipulated in the nuclear agreement, according to Al Alam.

“The main problem for the negotiations now is in the American capital, Washington. It is natural for the Europeans, more than ever, to seek a solution to the issue of the nuclear agreement due to the current situation and the strong pressures they are exposed to as a result of the outbreak of the Ukrainian war and the rise in oil prices. But the cause of the American problem is due to the internal politics of this country. The Iranian delegation has succeeded so far in properly following up on many of its demands and achieving them. This success caused disputes within the American negotiating delegation that even led to the resignation of some members of the American delegation, including Richard Nephew, author of the book ‘The Art of Sanctions.’ Thus, there were prominent differences within America over the negotiating approach of the American delegation, which created difficulties in the way of continuing the American administration's work in this field. This caused the U.S. administration to not show the necessary will to return to the agreement” he stated.

Marandi added, “But as I mentioned, the outbreak of the Ukrainian war and the exacerbation of problems for the Americans and Europeans raised the cost of stopping the negotiations for them. On the other hand, the U.S. Congress's reaction to Robert Malley's report on the negotiations was very negative. Members of Congress protested against the ‘great retreat’ of the U.S. administration vis-à-vis Iran.”

Responding to a question about the reason for the U.S. administration's reluctance to take the decision, the adviser to the Iranian negotiating team said, “It is clear that there is now a serious dispute between the Biden administration on the one hand, and Congress, especially the Republicans who are opposed to returning to the nuclear agreement, on the other. The increase in this tension has put the U.S. administration at a crossroads, and the closer we get to the U.S. elections, the more difficult it becomes for Biden to make a decision, and this is at a time when Biden needs to urgently resolve the issue of the nuclear agreement due to the Ukrainian war in order to devote himself to the Ukrainian issue after settling the rest of foreign policy issues.”

He pointed out, “Time is running out for the U.S. administration before the U.S. elections, and the possibility of an agreement in Vienna has declined, but the American and European desire for an agreement has increased due to the pressures of the Ukrainian war amid the decline in European and American economic performance.”

As regards the differences over delisting the Islamic Revolution Guards Corps (IRGC), Marandi said, “If America now agrees to remove the entire name of the Revolutionary Guards from its list, the situation will not change, and we cannot talk about consensus about returning to the nuclear agreement. Because there are now a number of outstanding and remaining issues, the most important of which is the issue of guarantees that the U.S. administration must provide. So far, this administration has not even accepted to give guarantees about its commitment to the nuclear agreement during the Biden era. Foreign investors do not dare to enter the Iranian market if there are no guarantees. This clearly affects our economic interests, so there is no possibility of an agreement being reached if there are no guarantees for the U.S. administration's commitment.”

The adviser to the Iranian negotiating delegation stressed that the U.S. administration is not ready to give guarantees about its continued commitment to the nuclear agreement, even when its positions are announced.

“Iran even agreed that the Biden administration would guarantee its commitment to the nuclear agreement until the end of its term, but the U.S. administration did not accept this either. So why should Iran commit itself to this fragile agreement?” he asked.