An interim nuclear deal between Iran and six world powers will start on January 20th.
Under the terms of the agreement, which was reached in November, Iran will see some sanctions suspended as soon as the deal takes effect.
Tehran has agreed to halt enrichment of uranium above five-percent purity, and "neutralize" its stockpile of near-20-percent-enriched uranium.
The deal gives world powers and Tehran six months to agree on a complete end to a standoff that has raised the risk of a wider Middle East war.
U.S. President Barack Obama welcomed the news but U.S. Secretary of State John Kerry cautioned that the next stage in negotiations would be "very difficult."
The EU's foreign policy chief Catherine Ashton said the world powers will ask the International Atomic Energy Agency to verify the deal's implementation.