Risking the ire of the United States, world powers launched a new financial mechanism on Friday that is meant to overcome American sanctions on Iran and salvage the 2015 nuclear deal.

The announcement of the launch of Instex came following an hours-long meeting in Vienna between Iranian officials and other signatories to the Joint Comprehensive Plan of Action, the landmark nuclear deal meant to restrict Iran’s nuclear programme, just days before Iran was to breach limits on its uranium enrichment stockpile because it said other parties were failing to meet their obligations.

“Instex [is] now operational,” European Union foreign policy secretary general Helga Schmid tweeted. “First transactions being processed, and other EU member states to join.”

Iran’s envoy to the meeting, deputy foreign minister Abbas Araqchi, said the launch amounted to “a step forward”, but he doubted it would suffice.

He demurred on whether Iran would hold off on breaching reactor grade stockpile limit of 300kg.

Tensions high as Trump approves new Iran sanctions: In pictures Show all 17 1 /17 Tensions high as Trump approves new Iran sanctions: In pictures Tensions high as Trump approves new Iran sanctions: In pictures Iran claims that in this picture released by Iran state TV, their surface-to-air missile is seen as it shoots down a US surveillance drone EPA Tensions high as Trump approves new Iran sanctions: In pictures This photo shows US RQ-4A Global Hawk unmanned surveillance drone. A drone of this model was shot down by Iran on Thursday 21 June AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures An oil tanker is on fire after it was subject to a suspected attacked at the Gulf of Oman on June 13. The US has blamed Iran for the attack Reuters Tensions high as Trump approves new Iran sanctions: In pictures Iran claims that in this picture released by Iran state TV, debris from the downed US drone is seen after it was recovered from Iranian waters AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures Smoke billows from an oil tanker after it was subject to a suspected attacked at the Gulf of Oman on June 13 Reuters Tensions high as Trump approves new Iran sanctions: In pictures US President Trump holds up a signed executive order to increase sanctions on Iran on 24 June AP Tensions high as Trump approves new Iran sanctions: In pictures Iranian President Rouhani stated in a televised address that the White House is "afflicted by mental retardation" following the increase in sanctions on 25 June EPA Tensions high as Trump approves new Iran sanctions: In pictures An Iranian navy boat tackles the fire on the Norwegian owned Front Altair oil tanker after it was hit in a suspected attack AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures Iran claims that in this picture released by Iran state TV, debris from the downed US drone is seen after it was recovered from Iranian waters AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures Smoke billows from an oil tanker after it was subject to a suspected attacked at the Gulf of Oman on June 13 Reuters Tensions high as Trump approves new Iran sanctions: In pictures A screenshot from a video released by the US Department of Defense that the US claims to show Iranian removing an unexploded limpet mine form the hull of the Japan-owned ship that was attacked in the Gulf of Oman on June 13 Getty Tensions high as Trump approves new Iran sanctions: In pictures An item reportedly found on the Japan-owned oil tanker that was attacked on June 13 in the Gulf of Oman AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures A handout photograph from the US Department of Defense shows a composite material that the US claim was left behind on the hull of the Japan-owned oil tanker following the removal of an unexploded limpet mine Getty Tensions high as Trump approves new Iran sanctions: In pictures A view from the cabin of an Iranian navy boat as it tackles the fire on the Norwegian owned Front Altair oil tanker after it was hit in a suspected attack EPA Tensions high as Trump approves new Iran sanctions: In pictures Release by US government A picture released by U.S. Central Command shows damage to the hull of the oil tanker Kokuka Courageous. The picture suggests that the ship is 'likely' to have been hit by a mine as the US Secretary of State Mike Pompeo moves to blame Iran for the suspected attack Reuters Tensions high as Trump approves new Iran sanctions: In pictures Smoke billows from an oil tanker after it was subject to a suspected attacked at the Gulf of Oman on June 13 Reuters Tensions high as Trump approves new Iran sanctions: In pictures Release by US government A picture released by U.S. Central Command shows damage to the hull of the oil tanker Kokuka Courageous. The pictures suggests that the ship is 'likely' to have been hit by a mine as the US Secretary of State Mike Pompeo moves to blame Iran for the suspected attack EPA

“I do not think that the progress made in the talks today is enough to dissuade Iran from changing its stance on the limits set in the nuclear deal,” Mr Araqchi told Iranian state television.”A report on the meeting will be sent to Tehran and they will make a decision.”

Iran is to announce further potential accelerations of its nuclear programme on 7 July.

The launch of Instex, months in the works, came following a dramatic day of diplomatic manoeuvring meant to save the nuclear deal.

The agreement has been imperilled since the administration of Donald Trump last year pulled out of it and, goaded by Washington hardliners, launched a campaign of maximum pressure, ostensibly to draw Iran back to the negotiating table.

It has vowed to flex its considerable economic might and oversight over the global financial system to punish any country or entity purchasing Iranian energy exports, severely damaging Iran’s economy.

Donald Trump says US 'won't need an exit strategy' in war with Iran

The other signatories to the agreement – the UK, France, Russia, Germany, and China – vowed to maintain the deal, which promised Iran normalised economic ties and nuclear cooperation in exchange for curtailing and opening up its atomic programme.

But progress has been lagging, and Iranians announced they would begin to step up production of reactor grade uranium, and consider other steps, including enriching to higher levels and even leaving the international Non-Proliferation Treaty.

Throughout the day on Friday, diplomats in Vienna and elsewhere strived to preserve the deal, which was enshrined into international law by a vote of the UN Security Council and seen by many as a way to avoid the risk of war and nuclear proliferation in the already volatile Middle East.

Countries that were not signatories to the deal – Austria, Belgium, Finland, the Netherlands, Slovenia, Spain and Sweden – issued statements in support. And China hinted that it would ignore US sanctions on oil purchases from Iran.

Jeremy Hunt says UK would not join US in war against Iran

The last-minute launch of Instex will likely encourage Iranians to avoid bursting through uranium enrichment caps immediately, and provide a means for Iran to purchase and sell goods which are not under US sanction.

“The strength of Instex is in its declared humanitarian focus, which shields it from US pressure and also maximises the likelihood that European companies will engage the currently untested mechanism,” Esfandyar Batmanghelidj, founder of Bourse & Bazaar, and Sahil Shah, a fellow at the European Leadership Network, write in a paper about Instex released on Friday.

But others worry that without a means for Iran to sell its oil to countries without incurring the wrath of the US, it merely buys time. The US has said that it has no objection to Instex so long as it is used for food and medicine, but has also looked warily at it, and is being encouraged by a clique of Washington hardliners that appear to shape Mr Trump’s Iran policy to sabotage it.