If that fails, however, the US could take a more combative stance and threaten to use direct military force, the sources were quoted as saying.
Meanwhile, Britain, France and Germany have informed the UN Security Council of their willingness to reimpose "snap back" international sanctions on Iran over its nuclear programme, Reuters reported on Thursday.
"Iran must de-escalate its nuclear programme to create the political environment conducive to meaningful progress and a negotiated solution," the UN ambassadors of the so-called E3 countries wrote in a Dec. 6 letter to the Security Council.
"We reiterate our determination to use all diplomatic tools to prevent Iran from acquiring a nuclear weapon, including using snap back if necessary," they added.
The threat comes after International Atomic Energy Agency (IAEA) head Rafael Grossi confirmed that Tehran had in recent weeks sharply increased its uranium enrichment.
“Today the agency is announcing that the production capacity is increasing dramatically, of the 60 per cent inventory,” said Grossi at the Manama Dialogue security conference in Bahrain on Dec. 6.
The Islamic Republic already has enough 60 per cent-enriched uranium for four nuclear weapons in principle, should Tehran decide to enrich it further to the roughly 90 per cent level needed, according to Reuters.
Enrichment is set to rise to “seven, eight times more, maybe, or even more” than the previous rate of 5-7kg a month, said Grossi, according to the report.
IAEA inspectors detected the increased enrichment activities at Iran’s Fordow nuclear plant south of Tehran, he told the BBC.
The international community will lose the ability to snap back sanctions on the Islamic Republic when restrictions set forth in U.N. Security Council Resolution 2231 (2015) expire on Oct. 18, 2025. The resolution enshrined the Obama-led Iranian nuclear deal with Britain, France, Germany, Russia, China and the United States.
Trump withdrew Washington from the Joint Comprehensive Plan of Action in 2018, arguing that it did not sufficiently curb Tehran's path to acquiring the bomb.
Last week, Britain, France and Germany agreed to continue nuclear negotiations with Tehran following a meeting in Geneva and amid threats by Trump to reinstitute a “maximum pressure” campaign on the Islamic Republic once he assumes office in January.
Iran’s nuclear negotiator Deputy Foreign Minister Majid Takht-Ravanchi met on Nov. 29 with top diplomats from the European nations.
The talks came after the European countries joined the United States to have Iran censured by the IAEA for its lack of cooperation.
The resolution by the agency’s 35-nation Board of Governors notes an “essential and urgent” need for Iran to provide “technically credible explanations” for the uranium traces at undeclared facilities. It also urges the IAEA to compile “a comprehensive and updated assessment on the possible presence or use of undeclared nuclear material in connection with past and present outstanding issues regarding Iran’s nuclear program.”
Iran condemned the censure as “politically motivated” and announced the launch of “new advanced centrifuges” to produce additional enriched uranium.
In a letter to the Security Council on Monday, Iran's U.N. Ambassador Amir Saeid Iravani called on the E3 nations to "abandon their ineffective and failed policy of pressure and confrontation."
Instead, the countries "should embrace diplomacy and focus on rebuilding the trust essential to resolving the current impasse," said Saeid Iravani.
On Tuesday, UN Secretary-General António Guterres submitted his biannual report to the Security Council on the implementation of Resolution 2231, warning there was a "critical need for a peaceful solution to the Iranian nuclear issue."
The "snap back" of international sanctions would require Iran to suspend all nuclear enrichment and reprocessing activities and ban related imports. It would also reimpose an arms embargo, bar Tehran development of nuclear-capable ballistic missiles and reimpose sanctions on targeted individuals and entities.
With reporting by Jewish News Syndicate
