Speaking at a Monday press briefing about the Fordow site, Mike Pompeo said there was no legitimate reason for Iran to resume enrichment at Fordow.
"President [Hassan] Rouhani recently announced that Iran will begin uranium enrichment activities at the Fordow facility. Therefore, the United States will terminate the sanctions waiver related to the nuclear facility at Fordow, effective December 15th, 2019," he told the briefing.
He said Iran should not be allowed to enrich uranium at any level, and it must "reverse its activity" at Fordow facility "immediately".
His comments came more than a week after Tehran announced the resumption of uranium enrichment at the site as part of its measure to scale back compliance with the 2015 nuclear deal over other signatories’ failure to fulfill their obligations.
Under the Joint Comprehensive Plan of Action (JCPOA), Iran was allowed to maintain centrifuges at Fordow for research purposes, and the first-generation IR-1 centrifuges were only allowed to spin without uranium gas.
However, the country started injecting UF6 (uranium hexafluoride) gas into centrifuges under the supervision of inspectors from the International Atomic Energy Agency (IAEA) earlier this month.
Iran says it has officially started injecting gas into hundreds of centrifuges at Fordow nuclear facility in fourth step away from the 2015 nuclear deal.
The Islamic Republic says the suspension of its commitments is not a violation of the JCPOA, adding it is based on Articles 26 and 36 of the agreement itself, which detail mechanisms to deal with non-compliance.
The fate of the Iran deal has been in doubt since May 2018, when the US abruptly abandoned the deal and reinstated all the anti-Iran sanctions that it had lifted as part of the JCPOA.
Tehran says the European signatories — Britain, Germany and France — have so far failed to uphold their commitments. They have expressed vocal support for the deal, but failed to provide meaningful economic incentives as required under the nuclear agreement.
Despite its withdrawal from the deal and the re-imposition of its sanctions on Iran, the US had granted sanctions waivers to allow Europe, China and Russia to cooperate with the Islamic Republic on a number of nuclear facilities in Iran, including Fordow.