Iran's Supreme Leader Ayatollah Mojtaba Khamenei has issued a directive that the country’s near-weapons-grade uranium must not be sent abroad, senior Iranian sources said, hardening Iran’s position on a key U.S. demand in ongoing peace talks.

"The Supreme Leader’s directive, and the consensus within the establishment, is that the stockpile of enriched uranium should not leave the country,” said one of the two Iranian sources, who spoke on condition of anonymity because of the sensitivity of the matter.

Iran's top officials, the sources said, believe that sending the material abroad would leave the country more vulnerable to future attacks by the United States and Israel. Khamenei has the last say on the most important state matters.

Khamenei's order could further frustrate U.S. President Donald Trump and complicate talks on ending ⁠the U.S.-Israeli war on Iran.

The White House and Iran's foreign ministry did not respond to requests for comment.

Israeli officials have told Reuters that Trump has ⁠assured Israel that Iran's stockpile of highly enriched uranium, needed to make an atomic weapon, will be sent out of Iran and that any peace deal must include a clause on this.

The two sides have started to narrow some gaps, the sources said, but deeper splits remain over Tehran's nuclear program – including the fate of its enriched uranium stockpiles and Tehran's demand for recognition of its right to enrichment.

Iranian officials have repeatedly said Tehran’s priority is to secure a permanent end to the war and credible guarantees that the U.S. and Israel will not launch further attacks.

Only after such assurances are in place, they said, would Iran be prepared to engage in detailed negotiations over its nuclear program.