A handout picture provided by Iranian presidential office on Feb 10, 2021 shows Iranian President Hassan Rouhani speaking in a live TV speech marking the 42nd anniversary of the 1979 Islamic Revolution, in Tehran. (IRANIAN PRESIDENCY / AFP)

TEHRAN - Iranian President Hassan Rouhani on Thursday criticized Washington for the delay in reembracing its commitments under the 2015 nuclear deal, commonly known as the Joint Comprehensive Plan of Action (JCPOA).

As Iran's Supreme Leader Ayatollah Ali Khamenei has said, if the United States returns to the JCPOA, Iran will also return to its commitments, Rouhani was quoted as saying by the state TV.

Iran has begun enriching uranium with a fourth cascade, or cluster, of advanced IR-2m machines at its underground Natanz plant, according to a report by the International Atomic Energy Agency

"This would mean a win-win bargain for the region and the entire world, which would benefit them. The Americans were not able to understand that, and they have failed to seize this golden opportunity," he noted.

They have been dragging their feet, which shows this new US government is far from understanding the reality about Iran, the Iranian president said.

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Washington under former President Donald Trump withdrew from the JCPOA in 2018 and tightened sanctions on Iran. In response to the US moves, Iran has suspended implementation of parts of its obligations under the deal.

Meanwhile, Iran has begun enriching uranium with a fourth cascade, or cluster, of advanced IR-2m machines at its underground Natanz plant, according to a report by the International Atomic Energy Agency.

“On 31 March 2021, the Agency verified at FEP that: Iran had begun feeding natural UF6 into a fourth cascade of 174 IR-2m centrifuges,” the IAEA said in its confidential report dated Wednesday and obtained by Reuters on Thursday. By UF6, it was referring to uranium hexafluoride, the form in which uranium is fed into centrifuges for enrichment.

Iran has informed the IAEA that it plans to use six cascades of IR-2m machines at the FEP to refine uranium up to 5 percent fissile purity. The report said the remaining two cascades were installed but not yet enriching. Installation of a planned second cascade of IR-4 machines had not yet begun, it added.

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“In summary, as of 31 March 2021, the Agency verified that Iran was using 5,060 IR-1 centrifuges installed in 30 cascades, 696 IR-2m centrifuges installed in four cascades and 174 IR-4 centrifuges installed in one cascade to enrich natural UF6 up to 5 percent U-235 at FEP,” said the report, sent to IAEA member states.

With Reuters inputs