Iran’s nuclear energy agency indicated Tuesday that Tehran would soon begin injecting gas into the latest generation of advanced centrifuges, IR-8, in a move that marks the next step to make them operational and that Iran says is permitted under the terms of the nuclear deal signed last year with six world powers.

“The IR8 tests have come to an end and they will go into the stage of gas injection in the next few weeks,” a spokesman for the Atomic Energy Organization of Iran (AEOI), Behrouz Kamalvandi, announced at a press conference on Tuesday, according to the semi-official Fars new agency.

The report added that this step will proceed in accordance with “the nuclear deal that allows research activities on the eighth generation of Iran’s centrifuge machines, known as the IR-8.”

Iran has said that its IR-8 centrifuges enrich uranium 20 times faster than the IR-1 centrifuges, which the country used prior to the deal.

Under the terms of the agreement as issued in a fact sheet released by the US State Department last year, Iran “will not use its IR-2, IR-4, IR-5, IR-6, or IR-8 models to produce enriched uranium for at least ten years. For ten years, enrichment and enrichment research and development will be limited to ensure a breakout timeline of at least 1 year. Beyond 10 years, Iran will abide by its enrichment and enrichment R&D plan submitted to the IAEA, and pursuant to the JCPOA, under the Additional Protocol resulting in certain limitations on enrichment capacity.”

Iran has maintained that, under the accord, it was allowed to conduct R&D on its more advanced centrifuges.

Last week, American lawmakers voted to extend some sanctions against Iran for another 10 years and although President Barack Obama declined to sign the act it still became law.

In response, Iran’s Foreign Minister Mohammad Javad Zarif sent a a letter to the European Union foreign policy chief Federica Mogherini, calling for a joint commission meeting on the nuclear deal.

Iran believes the US has violated the nuclear deal by renewing the Iran Sanctions Act, which eased sanctions in exchange for curbs on Iran’s nuclear program.

US president-elect Donald Trump during his campaign labeled the deal, which saw punishing economic sanctions on Iran lifted, a “disaster” and threatened to tear it up.

Last month, the head of the UN atomic watchdog chided Iran after a second minor breach this year by Tehran of the 2015 nuclear deal.

A report by the International Atomic Energy Agency in November showed that Iran’s stock of so-called heavy water had inched above the level agreed under the landmark accord.

Heavy water, a modified form of normal water, is used in certain types of nuclear reactors.

“Iran has since made preparations to transfer a quantity of heavy water out of the country,” which will bring it below the ceiling, IAEA chief Yukiya Amano told the agency’s board.

“It is important that such situations should be avoided in future in order to maintain international confidence in the implementation” of the deal, he said in Vienna.

The July 2015 nuclear deal between Iran and six major powers states that Iran’s “needs” are estimated to be around 130 metric tons of heavy water.

The confidential IAEA report, seen by AFP, said that Iran exceeded this level by 100 kilograms but that Iran had undertaken to export five tons.