U.S. Secretary of State John Kerry emerged from talks Sunday with Iranian Foreign Minister Mohamad Javad Zarif, saying Washington was intent on advancing negotiations focused on reducingIran's atomic activities in exchange for an end to nuclear-related sanctions.

The talks have been stalled for months over Iran's opposition to sharply reducing the size and output of centrifuges that can enrich uranium both to levels needed for reactor fuel or the core of nuclear warheads. Iransays its enrichment program is only for peaceful purposes, but Washington fears it could be used to make a bomb. Iran says any deal must put an end to the sanctions that have crippled the Iranian economy.

Kerry "noted that this week is an opportunity to make additional progress and stressed that it is our intention to do so," according to a readout of the meeting by a senior State Department Official, speaking on background, who said the two met for over an hour at a hotel. The official said Kerry and Zarif "agreed to meet further as needed while in New York."

The official said Kerry and Zarif also discussed "the threat posed by ISIL," another name for the Islamic State group that has seized vast swaths of territory in Iraq and Syria. Shiite Iran and the U.S. share a common enemy in the Islamic State militant group, but a deep-seeded lack of trust has so far kept the longtime foes from publicly joining hands in a coalition to defeat the Sunni extremists. In Iraq, the U.S. has been conducting airstrikes against Islamic State fighters, while Iran has backed Iraqi Shiite militias leading some of the fighting against the extremist group.

The latest round in the nuclear talks began at the United Nations on Friday, bringing Iran to the negotiating table with the United States, Russia, China, Britain, France and Germany. With time running out before a Nov. 24 deadline, there were indications that Washington was trying a new approach to break the impasse.

Diplomats told The Associated Press on Saturday that a new U.S. proposal on the table focuses on removing piping connecting the centrifuges. That would allow the U.S. leeway on modifying demands that Iran cut the number of centrifuge machines from 19,000 to no more than 1,500.

Only a proposal for now, the plan would allow the Iranians to claim that they did not compromise on vows that they would never emasculate their enrichment capabilities, while keeping intact American demands that the program be downgraded to a point where it could not be quickly turned to making bombs.

But any plan could founder due to opposition to major compromises from Iranian hardliners as well as U.S. congressional critics.

Warning of "troubling nuclear concessions to Iran," a group of 31 Republican senators expressed grave concerns about the new initiative and the possible softening of Washington' stance on other issues, in a letter dated Sept. 19 and sent to Kerry.

Other contentious issues are what to do with an underground enrichment plant near the village of Fordo and with a reactor under construction near the city of Arak.

The U.S. wants the underground Fordo facility converted to non-enrichment use because it's heavily fortified against attack. And it wants the reactor converted to reduce to a minimum its production of plutonium, an alternate pathway to nuclear arms.

The deadline was extended to Nov. 24 after the sides failed to reach agreement by the end of July.