Iran has met a key requirement of a nuclear deal with six world powers by allowing Moscow to transfer most of its enriched uranium to Russia, a senior Russian diplomat told The Associated Press Monday.

The diplomat demanded anonymity because he was not authorized to be identified by name.

Under the July 14 deal, Iran must ship out all except 300 kilograms (over 660 pounds) of the close to nine tons of low-enriched uranium it has stockpiled. Low-enriched uranium is suited to power generation but can be further enriched to arm nuclear warheads.

Its removal is a key obligation taken on by Iran under the deal, which aims to reduce its ability to make nuclear weapons — something Tehran says it has no interest in. The agreement also commits Iran to sharply reduce the number of centrifuges, which are used to enrich uranium, as well as to re-engineer a reactor to cut its output of plutonium — another pathway to nuclear weapons.

In exchange for those and other moves meant to constrain Iran’s ability to make such arms for more than a decade, most international sanctions imposed on Tehran over its nuclear programs will be lifted. That will happen after the U.N’s International Atomic Energy Agency confirms that Iran has met all commitments.

That stage of the deal, known as implementation day, is expected sometime next month.

(AP)