In early January, Iran announced that it had resumed research on enriching uranium, which can be used to produce nuclear weapons. In July, the UN Security Council passed Resolution 1696, which requires Iran to halt its enrichment of uranium and all other "research and development" activities or face the threat of sanctions. Despite this, Iran has taken a hard stance. In late December, Russia and the European Union threatened Iran with economic sanctions if it fails to suspend uranium enrichment. Picture shows a sample of uranium enrichment.