A former deputy of the International Atomic Energy Agency warned on Wednesday that Iran could enrich enough uranium for a nuclear bomb within six to eight months.

“Iran is actually weaponizing uranium enrichment without making a weapon,” said Olli Heinonen on Israel’s Army Radio, adding that based on his “perhaps back-of-the-envelope” estimate, Iran could acquire an enriched nuclear weapon in six to eight months “if they put in their maximum effort.”

However, Heinonen, currently a senior adviser on science and nonproliferation at the Foundation for Defense of Democracies and a senior fellow at Harvard University’s Kennedy School of Government’s Belfer Center for Science and International Affairs, criticized the Trump administration withdrawing in May 2018 from the 2015 Iran nuclear deal.

“I think [Iran] felt comfortable [with the Trump decision]. They have the enrichment technology and they can create more centrifuges,” he said. “Probably they [will be] able to withstand a lot of sanctions.”

While in Israel, Heinonen met with Israeli Prime Minister Benjamin Netanyahu on Thursday.

“It’s very clear Iran is lying. Iran is continuing to work towards an arsenal of nuclear bombs, and we’re committed to stop it,” said Netanyahu. “Thank you for your forthright analysis and your clear-cut conclusion. I thank you for pointing out what Iran is doing.”