Iranian Supreme Leader Mojtaba Khamenei issued a directive prohibiting Iran's stockpile of enriched uranium from being removed from the country, according to two senior Iranian sources. The United States has insisted publicly that Iran will not be allowed to retain its highly enriched uranium (HEU), including more than 440 kilograms enriched to 60% purity. One of the Iranian sources said that it could be possible to dilute the HEU under the supervision of the International Atomic Energy Agency (IAEA).