President Donald Trump clarified that the proposal for a nuclear deal with Iran bans the Islamic Republic from continuing to enrich uranium. Trump’s statement comes on the heels of reports that the deal submitted for Iran’s review allows Tehran to continue limited, low-level uranium enrichment. Iran has stressed that it is unwilling to suspend uranium enrichment, with senior leaders stressing that the issue is non-negotiable for the Islamic Republic.

“if the aim is to deprive Iran of its basic rights like low-level uranium enrichment, we don’t believe such negotiations would succeed,” Iranian Foreign Ministry spokesman Esmaeil Baqaei said last week.

“Iran’s enrichment is a real, accepted matter. We are ready to build confidence in response to possible concerns, but the issue of enrichment is non-negotiable,” Iranian Foreign Minister Abbas Araghchi said in April, responding

Tehran claims that it is enriching uranium for civilian purposes. Numerous watchdog groups have warned the purity of the uranium enriched by Iran is far above what is needed for energy uses, and suggests that Tehran is approaching the levels needed to create a nuclear weapon.

On Monday, Iranian officials signaled via the media that they were preparing to reject Trump’s proposal. “Iran is drafting a negative response to the U.S. proposal, which could be interpreted as a rejection of the U.S. offer,” a senior diplomat told Reuters. Last week, Trump expressed optimism about a potential agreement that would curb Iran’s nuclear program.

“We’ve had some very, very good talks with Iran,” Trump told reporters. “And I don’t know if I’ll be telling you anything good or bad over the next two days, but I have a feeling I might be telling you something good.”