Iranian and U.S. officials cited significant progress Wednesday in international talks on Iran’s nuclear program, agreeing to hold further meetings in rapid succession with the aim of producing a deal inhibiting Tehran’s ability to acquire atomic weapons.

The two days of talks in a palace just above Lake Geneva yielded no specific agreements on curbing Iran’s nuclear activities. But they produced a rare direct meeting between U.S. and Iranian officials and pledges from both sides to work quickly to end what a top Iranian official called “an unnecessary crisis.”

“We have had two days of extensive and fruitful consultations . . . which will hopefully be the beginning of a new phase in our relations,” Iranian Foreign Minister Mohammad Javad Zarif told reporters at the conclusion of the talks between Iran and a bloc of six world powers known as the P5-plus-1.

The modest tangible results — a schedule for further negotiations early next month and, for the first time in four years, an agreement on the wording of a short concluding statement — masked what several officials described as a significant change in tone compared with previous nuclear talks. Western officials said the Iranian position reflected a continuation of a more pragmatic style that has come to define the country’s foreign policy since the election of moderate cleric Hassan Rouhani as president.

In Washington, White House spokesman Jay Carney said the Iranian proposal “was new and represents a level of seriousness and substance we have not seen before.” He cautioned, though, that “no one should expect a breakthrough overnight.”

Most of the discussions in Geneva revolved around a confidential proposal presented by Zarif as the talks began Tuesday. The veteran diplomat, using PowerPoint slides, laid out what Iranian officials described as a “road map” that called for resolving the nuclear dispute over several stages within a year.

Diplomats insisted that details of the plan would be kept private while the negotiations were underway. However, Iranian and Western officials said the proposal called for concessions by Iran and a gradual easing of Western sanctions, which have crippled the country’s economy. Iranian officials also described a proposed final resolution that would preserve their country’s right to a peaceful nuclear energy program, but “without any proliferation concerns,” in Zarif’s words.

U.S. officials described the Iranian proposal as extremely detailed and said there were numerous areas of disagreement.

“There is more work — much more work — to do, as we knew there would be,” said a senior Obama administration official, speaking on the condition of anonymity to discuss the sensitive deliberations with Western journalists. “Any agreement has to give the United States and the world every confidence that Iran will not acquire a nuclear weapon.”

‘Substantive’ negotiations

Western and Iranian diplomats said the talks were intense but cordial as the delegations hashed over ideas in small bilateral meetings and larger plenary sessions. Unlike in previous negotiations, Zarif spoke in English, allowing a free-flowing debate uninterrupted by lengthy translations.

As the talks entered a second day, Zarif visibly struggled with a bout of back pain that prompted him to seek treatment from an acupuncture specialist. His obvious discomfort prompted expressions of sympathy and advice from other diplomats, according to Western officials present at the meetings.

At the end, the joint statement approved by the sides was read at a packed news conference by Catherine Ashton, the European Union’s foreign policy chief and the chief interlocutor for the P5-plus-1 group, which includes the United States, Britain, China, France, Germany and Russia. The statement set a Nov. 7 date for the start of the next round of formal talks, preceded by a separate discussion among technical experts.

The statement called the Geneva talks “substantive and forward looking,” and it described Zarif’s outline as a “proposed basis for negotiation, which is being carefully considered.”

The talks began in an air of expectancy after diplomatic overtures by senior Iranian officials. Rouhani, who campaigned on a pledge to end Iran’s international isolation and gain relief from the sanctions, has embarked on a diplomatic charm offensive in recent weeks, capped by last month’s 15-minute phone call with President Obama, the first direct contact between the leaders of the United States and Iran in three decades.

The P5-plus-1 group has failed to secure a deal with Iran in multiple rounds of negotiations over the past two years, as Iran continued to rapidly expand its capacity to produce enriched uranium. Western governments fear that Iran will soon possess enough fissile material to be able to assemble a nuclear bomb in only a few days or weeks, if it decides to do so.

Cautious tone from U.S.

While welcoming the Iranians’ more engaging style, administration officials sought to tamp down enthusiasm about prospects for a deal. White House officials acknowledge that they face a significant challenge in selling any agreement to a skeptical Congress, which is threatening to impose even tougher sanctions on Iran unless it freezes uranium enrichment.

Accordingly, the senior administration official declined to call the Geneva results a “breakthrough” but said the Iranian proposals were “serious enough that they ought to have a chance.”

“Everyone is trying to go do work here and to do real things,” the official said. “As a beginning, it was not a bad start.”

Aaron David Miller, a former State Department official and a veteran of past Middle East negotiations, said he thinks that the White House expects and even prefers an ambiguous outcome.

“Now it appears that the administration is a tough negotiator, not giving in to mullah charm offensives,” Miller said. “The same logic works for Rouhani and Zarif, too, for now: tough bargainers defending Iran’s interests against the demanding Americans.”

For now, he said, the sides had opened “a discussion channel” but “not yet a decision-making channel.”

Scott Wilson in Washington contributed to this report.