UNITED NATIONS/VIENNA: The US is considering softening present demands that Iran gut its uranium enrichment program in favor of a new proposal that would allow Tehran to keep nearly half of the project intact while placing other constraints on its possible use as a path to nuclear weapons, diplomats told The Associated Press.

The initiative, revealed late Thursday, comes after months of nuclear negotiations between Iran and six world powers that have failed to substantially narrow differences over the future size and capacity of Tehran’s uranium enrichment program. Iran insists it does not want atomic arms but the West is only willing to lift nuclear-related sanctions if Tehran agrees to substantially shrink enrichment and other activities that Iran could turn toward making such weapons.

The US, which fears Tehran may enrich to weapons-grade level used to arm nuclear warheads, ideally wants no more than 1,500 centrifuges left operating. Iran insists it wants to use the technology only to make reactor fuel and for other peaceful purposes and insists it be allowed to run at least the present 9,400 machines.

The tentative new US offer attempts to meet the Iranians close to half way on numbers, said two diplomats who demanded anonymity because their information is confidential. They said it envisages letting Iran keep up to 4,500 centrifuges but would reduce the stock of uranium gas fed into the machines to the point where it would take more than a year of enriching to create enough material for a nuclear warhead.

That, they said, would give the international community enough lead time to react to any such attempt.

The diplomats emphasized that the proposal is only one of several being discussed by the six powers — the US, Russia, China, Britain, France and Germany — and has not yet been formally submitted to the Iranians.

Other ideas also include letting Iran have more than 1,500 machines but removing or destroying much of the infrastructure needed to make them run — wiring, pipes used to feed uranium gas and other auxiliary equipment.

Both ideas 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.

The new proposals reflect Washington’s desire to advance the talks ahead of a Nov. 24 deadline that was extended from July. The current round began a week ago on the sidelines of the UN General Assembly, leading to speculation that foreign ministers of the negotiating nations would join in the talks. But the diplomats said that was no longer planned because of the lack of substantial progress.

The fates of a reactor under construction near the city of Arak and of an underground enrichment facility at Fordo are also contentious issues. The US and its Western allies want the reactor converted to reduce to a minimum its production of plutonium, an alternate pathway to nuclear arms. And they insist that the Fordo plant be shuttered or used for something other than enrichment because it is fortified and thought to be impervious to air attacks.

The US proposal drew opposition from Israel. The country’s Intelligence Minister Yuval Steinitz said in a statement that “Israel strongly objects” because it believes Iran is conducting experiments meant to “ignite the nuclear chain reaction in nuclear weapons.”

Under a “sneak-out” scenario, Western officials and experts say, Iran could build a uranium enrichment plant in secret to make bomb material unbeknownst to the UN nuclear watchdog, now empowered to visit only Tehran’s declared nuclear sites.

To counter this risk, they say, any breakthrough diplomatic settlement with Iran must grant the International Atomic Energy Agency (IAEA) broader surveillance powers in this vast country crisscrossed by remote, often inaccessible mountains and desert.