In a statement on Wednesday, the AEOI said the gas injection started at 00:00 (local time) Thursday upon the order of President Hassan Rouhani, who is also the head of the Supreme National Security Council.
The gas injection, which was completed under the full supervision of the International Atomic Energy Agency (IAEA), started after the transfer of a cylinder containing 2,000 kilograms of UF6 from Shahid Ahmadi Roshan nuclear facility of Natanz to Fordow nuclear plant, located near the city of Qom.
The underground facility in Fordow has 1,044 IR-1 centrifuges. The uranium hexafluoride gas is being injected into 696 centrifuges, and the remaining machines (348) are used for producing and enriching stable isotopes.
Spokesman for the AEOI Behrouz Kamalvandi says after the completion of the process, enrichment will resume at Fordow plant at the level of 4.5 percent by Saturday, when the inspectors will come back to check the process again.
The fourth step in Iran’s commitment reductions was initially announced by President Hassan Rouhani on Tuesday.
Rouhani confirmed in a tweet on Wednesday that the gas injection would begin later in the day.
The Islamic Republic says the suspension of its commitments is not a violation of the JCPOA but is based on Articles 26 and 36 of the agreement itself. The country has repeatedly said the moves are reversible in case other parties to the JCPOA live up to their commitments.
The fate of the Iran deal has been in doubt since May 2018, when the US abruptly abandoned the deal and reinstated the anti-Iran sanctions that it had lifted as part of the JCPOA.
Tehran says the European cosignatories — 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.