In the wake of suspected sabotage at Iran’s Natanz enrichment facility on 11 April, Iranian Deputy Foreign Minister for Political Affairs Abbas Araghchi in a letter to the Director-General of the International Atomic Energy Agency (IAEA) Rafael Mariano Grossi on 13 April announced that Iran would start the uranium enrichment at the level of 60%. Under the 2015 Joint Comprehensive Plan of Action (JCPOA) between Iran the P5+1 group of countries (the USA, UK, France, Russia, and China plus Germany) Iran agreed to limit its nuclear development in return for the lifting of sanctions. Under the JCPOA, Iran had committed to keep enrichment to 3.67%. However, after former US President Donald Trump withdrew from the deal and reimposed sanctions in 2018, Iran began reviving its nuclear programme and had increased its enrichment level to 20% in January.

Israel is widely suspected of being behind the apparent cyberattack at the electricity distribution network of Shahid Mostafa Ahmadi Roshan uranium enrichment centre in Natanz causing loss of power in the area and a fire that reportedly damaging a number of centrifuges. Atomic Energy Organisation of Iran (AEOI) spokesman Behrouz Kamalvandi said the incident had not caused any injuries to staff or resulted in pollution and that an investigation was underway.

Israeli press reports said it would set back Iran’s nuclear development by at least nine months. Israel's public radio quoted unidentified intelligence sources as saying Israel's Mossad had carried out the cyber attack, Reuters reported. Israel is also believed to be responsible for the explosion in July 2020, which destroyed Iran’s centrifuge assembly facility. In 2010, the Stuxnet computer virus, believed to have been developed by the USA and Israel, was discovered after it was used to attack Natanz.

This incident happened the day after Iran's President Hassan Rouhani had unveiled 133 new nuclear achievements in the provinces of Tehran, Markazi, Isfahan, Alborz and Qom to mark the 15th anniversary of the National Nuclear Technology Day. In a ceremony held via videoconference he had also given the order for Iranian scientists to begin injecting uranium hexafluoride gas to a pilot cascade of 164 new generation IR6 centrifuges at the Natanz enrichment facility. He further announced that Iran had started mechanical testing of new generation IR-9 centrifuges and had launched an assembly line for their production. 

Meanwhile talks in Vienna aimed at bringing the USA back into the JCPOA continued to be reported as positive, with negotiations ongoing. Araqchi who was in Vienna for those talks, said additional centrifuges with 50% more capacity would be added to the machines in Natanz. "There are 1,000 centrifuges that will be installed in Natanz, in addition to the 5,000, and the 60 centrifuges, which may have been damaged will be replaced." He said the Natanz incident had only served to strengthen Iran’s resolve for both progress in the nuclear field and progress in the negotiations.

On the decision to enrich uranium to 60%, he said this was needed for the production of certain drugs, namely radioisotope drugs. However, Iran's President Hassan Rouhani said on 14 April that the decision to boost uranium enrichment to 60% was a direct response to the Natanz attack.

Araqchi said: “We are entering the negotiations with strength and power, and our goal is to lift the sanctions altogether. Sanctions must be lifted completely, verified, and then Iran will return to its commitments. Iran's Foreign Minister Mohammad Javad Zarif said on 13 April following talks in Tehran with Russian Foreign Minister Sergei Lavrov that Israel had gambled and lost by sabotaging the Natanz nuclear facility.

Lavrov said he expected the Iranian nuclear deal to be saved and condemned recent EU sanctions against Iran, saying they could undermine ongoing nuclear talks. "We expect that it will be possible to preserve the JCPOA," Lavrov said. "As far as we understand, our partners in Tehran have expressed their readiness to immediately move in that direction" if Washington upholds the agreement at its end, Lavrov added.

The previous day the EU had added eight Iranian security officials, including the head of the Revolutionary Guards, and three prisons to a sanctions blacklist consisting of asset freezes and visa bans over a 2019 incident. “If there is any kind of coordination lacking in the EU and the right hand is not aware of what the left hand is doing, that's simply unfortunate," Lavrov said. "But if this decision has been deliberately taken while talks continue in Vienna to rescue the JCPOA then it is not just unfortunate — this is a mistake that is worse than a crime.”