Iran has started enriching uranium to a purity level beyond the limit it had agreed to in a nuclear deal with European powers and the United States in 2015. The breach of the pact, first announced by Tehran, was confirmed by the International Atomic Energy Agency on Monday.

A spokesperson for the agency said, quoting Director General Yukiya Amano, that inspectors had on Monday verified that Iran was enriching uranium above the 3.67% purity limit, Reuters reported. In a report, the agency told its member nations that Iran had acknowledged enriching uranium to about 4.5% purity. The International Atomic Energy Agency monitors Iran’s adherence to the 2015 deal.

Earlier on Monday, Atomic Energy Organization of Iran spokesperson Behrouz Kamalvandi had confirmed the purity level to AP news agency. He also told state TV that Iran might consider going to 20% enrichment or more.

Uranium with 3%-5% purity is typically used in nuclear reactors. Weapons-grade uranium has over 80% purity, but is not difficult to attain once the 20% level is reached.

Iranian President Hassan Rouhani had said on July 3 that Tehran was set to exceed the uranium enrichment limit. On Sunday, US President Donald Trump warned Iran against the move.

Last week, Iran announced that it had crossed the 300-kg limit of uranium stockpile set by the deal. The other signatories of the nuclear deal are struggling to keep it afloat after Donald Trump walked out of it last year and imposed crippling sanctions on the country again.