(Adds U.S. officials on implementation of the Iran deal)
WASHINGTON, Sept 17 (Reuters) - Stephen Mull, a former U.S. ambassador to Poland with experience working on nuclear and sanctions issues, will be the lead U.S. coordinator for implementing the July 14 nuclear deal with Iran, U.S. Secretary of State John Kerry said on Thursday.
"Steve will lead the interagency effort to ensure that the nuclear steps Iran committed to in the (Joint Comprehensive Plan of Action) are fully implemented and verified, and that we and our partners are taking reciprocal action on sanctions, following the nuclear steps," Kerry said in a statement.
Under the deal, sanctions imposed by the United States, the European Union and the United Nations will be lifted in return for Iran agreeing to long-term curbs on a nuclear program the West has suspected was aimed at creating a nuclear bomb.
Iran, which has denied that it seeks nuclear weapons, will mothball for at least a decade the majority of its centrifuges used to enrich uranium and sharply reduce its low-enriched uranium stockpile under the agreement.
Mull's previous assignments included serving from 2008 to 2010 as an aide to former under secretary of state Bill Burns, working on issues related to Iran's nuclear program and helping to design a U.N. Security Council resolution which imposed additional nuclear-related sanctions on Iran, Kerry said.
Several senior U.S. officials, who held a conference call with reporters after the announcement about Mull's appointment, described upcoming steps related to implementing the Iran nuclear deal. The U.S. Congress' 60-day review period ended on Thursday after Republicans failed to kill the agreement.
In the coming months, Iran, the International Atomic Energy Agency, the United States and other major powers will prepare for the deal's formal implementation, the officials said.
It remains unclear when the so-called "implementation day" will be. But the U.S. officials said the next key date is "adoption day" - October 18. This is the day when the U.S. administration will approve waivers for key U.S. sanctions on Iran to take effect on implementation day.
Iran must move to curtail its nuclear program to meet its commitments by implementation day, the officials added.
Western officials say international sanctions are unlikely to be lifted until next year. The timing depends on when Iran meets its commitments and the IAEA confirms Iran has resolved all outstanding issues with the agency.
If Iran fails to comply with the deal, the sanctions will be restored, the officials added. (Reporting by Arshad Mohammed in Washington and Louis Charbonneau in New York; Editing by Will Dunham and Christian Plumb)
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