Iran's nuclear stand-off with the West has been dragging for years, but there was a glimmer of hope Tuesday as Tehran presented new proposals to resolve the dispute.
Here is an overview of the issues on the table:
According to a Western diplomatic source, the P5+1 group -- the United States, Britain, France, China and Russia plus Germany -- are still making the same demands they presented to Iran during negotiations in Kazakhstan in February and May:
-- To dismantle the Fordo underground uranium enrichment facility near the central holy city of Qom. The existence of this site was revealed on September 25, 2009 on the margins of a G20 summit by the leaders of France, the United States and Britain.
-- To suspend 20-percent uranium enrichment, which international powers consider dangerously close to a weapons-grade capability.
-- To treat the country's remaining 20-percent enriched uranium and change it into combustible material.
In exchange, international sanctions could be lifted on Iran's exports of petrochemicals and precious metals.
The P5+1 are also seeking a tighter inspection regime under which officials from the UN nuclear agency IAEA can have free access to all Iran's nuclear sites. They also want to be able to go to the Parchin facility to check that no bombs are being made and to access a heavy-water plant at Arak that was formally opened in 2006.
Currently, Iran is only obliged to inform the IAEA three months ahead of transferring fissile material into the nuclear site.
THREAT OF NEW SANCTIONS
Draft legislation for new American sanctions targeting Iran's automobile sector and foreign reserves was adopted in July by the US House of Representatives, and had been due to come to the Senate for a vote in autumn.
But the senators have said they will freeze the implementation of the sanctions if Tehran immediately halts uranium enrichment.
However, Israel on Tuesday warned the world community to avoid a partial deal with Tehran which could see the easing of sanctions.
Israel has refused to rule out military strikes against Iran, with Prime Minister Benjamin Netanyahu telling the UN General Assembly this month that the Jewish state would act unilaterally if necessary.
Israel, the Middle East's sole if undeclared nuclear-armed power, wants Iran to meet four conditions before the sanctions are eased: halting all uranium enrichment, removing all enriched uranium from its territory, closing its underground nuclear facility in Qom and halting construction of a plutonium reactor.