(Headline USA) Iran and the United States held hours of indirect negotiations Thursday over Tehran’s nuclear program but walked away without a deal, leaving the danger of another Mideast war on the table as the U.S. has gathered a massive fleet of aircraft and warships in the region.

Oman’s Foreign Minister Badr al-Busaidi, who mediated the talks in Geneva, said there had been “significant progress in the negotiation” without elaborating.

But just before the talks ended, Iranian state television reported that Tehran was determined to continue enriching uranium, rejected proposals to transfer it abroad and sought the lifting of international sanctions, indicating it was not prepared to meet U.S. President Donald Trump’s demands.

Trump wants a deal to constrain Iran’s nuclear program, and he sees an opportunity while the country is struggling at home with growing dissent following nationwide protests. Iran also hopes to avert war, but maintains it has the right to enrich uranium and does not want to discuss other issues, like its long-range missile program or support for armed groups like Hamas and Hezbollah.

Al-Busaidi said technical talks involving lower-level representatives would continue next week in Vienna, the home of the International Atomic Energy Agency. The United Nations’ atomic watchdog likely would be critical in any deal.

In an interview with Iranian state television, Iran’s foreign minister said the talks with the U.S. were some of the country’s “most intense and longest rounds of negotiations.”

Abbas Araghchi offered no specifics but said “what needs to happen has been clearly spelled out from our side.”

If America attacks, Iran has said U.S. military bases in the region would be considered legitimate targets, putting at risk tens of thousands of American service members. Iran has also threatened to attack Israel, meaning a regional war again could erupt across the Middle East.

“There would be no victory for anybody — it would be a devastating war,” Araghchi told India Today in an interview recorded Wednesday just before he flew to Geneva.

“Since the Americans’ bases are scattered through different places in the region, then unfortunately perhaps the whole region would be engaged and be involved, so it is a very terrible scenario.”

Ali Vaez, an Iran expert with the International Crisis Group, said it was a good sign that the Americans did not walk away immediately Thursday when Iran presented its latest proposal.

“There might still not be a breakthrough at the end of this day, but the very fact that the U.S. team is returning shows that there is enough common ground between the two sides,” he said.

The two sides held multiple rounds of talks last year that collapsed when Israel launched a 12-day war against Iran in June and the U.S. carried out heavy strikes on its nuclear sites, leaving much of Iran’s nuclear program in ruins even as the full extent of the damage remains unclear.

Araghchi represented Iran at the talks. Steve Witkoff, a billionaire real estate developer and friend of Trump who serves as a special Mideast envoy, headed up the U.S. delegation with Trump’s son-in-law Jared Kushner. The talks again were mediated by Oman, an Arab Gulf country that’s long served as an interlocutor between Iran and the West.

The two sides adjourned after around three hours of talks and resumed the discussions later.

During the break, Iranian Foreign Ministry spokesperson Esmail Baghaei said the Iranians felt there were “constructive proposals” offered on both nuclear issues and sanctions relief.

Trump wants Iran to completely halt its enrichment of uranium and roll back both its long-range missile program and its support for regional armed groups. Iran says it will only discuss nuclear issues, and maintains its atomic program is for entirely peaceful purposes.

U.S. Secretary of State Marco Rubio told reporters Wednesday that Iran is “always trying to rebuild elements” of its nuclear program. He said that Tehran is not enriching uranium right now, “but they’re trying to get to the point where they ultimately can.”

Iran has said it hasn’t enriched since June, but it has blocked IAEA inspectors from visiting the sites America bombed. Satellite photos analyzed by The Associated Press have shown activity at two of those sites, suggesting Iran is trying to assess and potentially recover material there.

The West and the IAEA say Iran had a nuclear weapons program until 2003. After Trump scrapped the 2015 nuclear agreement, Iran ramped up its enrichment of uranium to 60% purity — a short, technical step away from weapons-grade levels of 90%.

U.S. intelligence agencies assess that Iran has yet to restart a weapons program, but has “undertaken activities that better position it to produce a nuclear device, if it chooses to do so.” Some Iranian officials have spoken openly about the country’s readiness to produce a bomb if that decision is taken.

If the talks fail, uncertainty hangs over the timing of any possible U.S. attack.

If the aim of potential military action is to pressure Iran to make concessions in nuclear negotiations, it’s not clear whether limited strikes would work. If the goal is to remove Iran’s leaders, that will likely commit the U.S. to a larger, longer military campaign. There has been no public sign of planning for what would come next, including the potential for chaos in Iran.

There is also uncertainty about what any military action could mean for the wider region. Tehran could retaliate against the American-allied nations of the Persian Gulf or Israel. Oil prices have risen in recent days in part due to those concerns, with benchmark Brent crude now around $70 a barrel. Iran in the last round of talks said it briefly halted traffic in the Strait of Hormuz, the narrow mouth of the Persian Gulf through which a fifth of all traded oil passes.

Adapted from reporting by the Associated Press.