Iran was to hold talks with Britain, France and Germany in Geneva on Friday over its nuclear programme, less than two months before Donald Trump returns as US president.
The meeting is shrouded in discretion, with the countries' foreign ministries giving away few details on what they will discuss -- or even where the talks are taking place.
Iranian diplomat Majid Takht-Ravanchi, the political deputy to Foreign Minister Abbas Araghchi, will represent Iran in Friday's talks, which follow on from a meeting in New York in September.
Laying the groundwork on Thursday, Takht-Ravanchi and deputy foreign minister for legal and international affairs Kazem Gharibabadi met with Enrique Mora, deputy secretary general of the European Union's foreign affairs arm.
Mora said on X that they held a "frank exchange... on Iran's military support to Russia that has to stop, the nuclear issue that needs a diplomatic solution, regional tensions (important to avoid further escalation from all sides) and human rights".
Friday's meeting takes place in the context of extreme tension in the Middle East between Iran and its allies, and Israel.
Prime Minister Benjamin Netanyahu said Thursday that Israel would do "everything" to stop Tehran acquiring a nuclear weapon after Araghchi warned Iran could end its ban on developing one if Western sanctions are reimposed.
The West's accusation that Tehran is supplying Russia with explosive drones for its war in Ukraine is further darkening the backdrop to Friday's talks.
And on January 20, Trump, who pursued a policy of "maximum pressure" against Iran during his first term, returns to the White House.
- IAEA chiding -
Friday's talks in Geneva have been overshadowed by the European countries teaming up with Washington to have Tehran censured by the UN atomic watchdog.
Last week, the 35-nation board of governors of the International Atomic Energy Agency adopted a resolution proposed by Britain, France, Germany and the United States condemning Iran for its lack of cooperation on nuclear issues.
The chiding at the IAEA prompted a defiant response from Tehran, which described the move as "politically motivated" and in response announced the launch of "new advanced centrifuges" designed to increase its stockpile of enriched uranium.
However, Iranian officials have since signalled willingness to engage with others ahead of Trump's return.
Iran insists on its right to nuclear energy for peaceful purposes, but according to the IAEA, it is the only non-nuclear-weapon state enriching uranium to 60 percent.
In an interview with The Guardian newspaper published Thursday, Araghchi warned that frustration in Tehran over unmet commitments, such as lifting sanctions, was fuelling debate over whether the country should alter its nuclear policy.
"We have no intention to go further than 60 percent for the time being, and this is our determination right now," he told the British daily.
But, he added, "there is this debate going on in Iran, and mostly among the elites... whether we should change our nuclear doctrine" as so far it has proven to be "insufficient in practice".
A 2015 nuclear deal between Tehran and major powers aimed to give Iran relief from crippling Western sanctions in exchange for limiting its nuclear programme to prevent it from developing a weapons capability.
Tehran has consistently denied any such ambition. Supreme leader Ayatollah Ali Khamenei, who has the final authority in Iran's decision-making, has issued a religious decree, or fatwa, prohibiting atomic weapons.
- 'Double disaster' -
For Tehran, the goal of Friday's talks is to avoid a "double disaster" scenario of renewed pressures from both Trump and European governments, according to political analyst Mostafa Shirmohammadi.
He noted that Iran's support in Europe had been eroded by allegations it offered military assistance for Russia's invasion of Ukraine.
Iran has denied these accusations and hopes to mend relations with Europe, while also maintaining a firm stance.
The Geneva talks come as the war of words between Iran and Israel have ratcheted up.
"I will do everything to prevent it from becoming a nuclear (power), I will use all the resources that can be used," Netanyahu told Israeli broadcaster Channel 14.
Israel is the region's sole, if undeclared, nuclear-armed state. It has long made preventing any rival from matching it its top defence priority.
Iran launched two missile barrages at Israel over the past year in retaliation for the killing of leaders from Hamas and Hezbollah, as well as an Iranian general.
Israel responded both times with limited attacks on Iran, most recently bombing several military sites on October 26.