Iran shipped 11 tonnes of low-enriched uranium material on Monday to Russia in accordance with the nuclear deal it reached with P5+1 countries on July 14.
The P5+1 countries - United States, United Kingdom, Russia, France, China and Germany - agreed to lift sanctions on Iran in exchange for it curbing its nuclear programme which they claimed was aimed at developing a nuclear weapon.
The reduction of Iran’s nuclear stockpiles to below 300 kg was one of the main pillars of the agreement.
The United States Secretary of State John Kerry welcomed on Monday the shipment of more than 11,340 kg (25,000 pounds) of Iranian low-enriched uranium is heading to Russia.
"This removal of all this enriched material out of Iran is a significant step toward Iran meeting its commitment to have no more than 300 kg of low-enriched uranium by Implementation Day," said Kerry after the shipment was sent.
“As we move ever closer to the implementation of the JCPOA [Joint Comprehensive Plan of Action], we will remain vigilant to ensure that its implementation achieves exactly what we set out to do from the very beginning of these negotiations, to ensure that Iran’s nuclear programme is and always remains exclusively for peaceful purposes."
Implementation Day is when the International Atomic Energy Agency (IAEA) is due to confirm Iran has met the requirements of the deal so the US and UN can start lifting the sanctions imposed on the country.
Enriched uranium can be used to build nuclear weapons and now that Iran has shipped away a major portion of its stock it would be much more difficult for it to do so.
Iran still has other steps to take, such as destroying the core of its Arak nuclear reactor, for the sanctions to be lifted.
The IAEA is responsible for confirming Iran has met its commitments and also monitoring the nuclear sites in the country to protect against any possible breach of the agreement.