MOSCOW (AP) — Russia’s state-controlled nuclear fuel company said Thursday it has suspended a joint research project with Iran because of its move to resume uranium enrichment.

The TVEL company that makes nuclear fuel components said in a statement that Iran’s decision to resume uranium enrichment at Fordo facility makes it impossible to convert the facility to produce radioactive isotopes for medical purposes.

The company noted that uranium enrichment is technologically incompatible with production of such isotopes. It added that Iran would need to disassemble the centrifuges used to enrich uranium and decontaminate the room to continue the medical project.

The company said it had informed Iran of its decision.

Iran agreed to stop uranium enrichment under a 2015 deal with world powers, but it has resumed such activities after the U.S. pulled out of the pact last year and imposed new sanctions.

Last month, Iran announced that it was resuming uranium enrichment at Fordo, a heavily fortified facility inside a mountain ringed by anti-aircraft batteries that has about 1,000 centrifuges.

Such a step is prohibited under the agreement Iran reached with world powers to prevent it from building a bomb. Tehran has maintained that its nuclear program is for peaceful purposes.

The 2015 deal envisaged the Russia-Iran project to turn Fordo into a research center and produce radioactive isotopes of tellurium and xenon for medical use. It was monitored by the International Atomic Energy Agency, the U.N. nuclear watchdog.