Israeli Prime Minister Benjamin Netanyahu has left Israel for Washington to present his arguments against a possible nuclear deal with Iran.
Netanyahu, at the invitation of Republican lawmakers, is scheduled to give a speech to both chambers of the U.S. Congress.
The scheduled speech has angered the White House, which was not consulted before the invitation was given.
Netanyahu disapproves of a potential deal now being negotiated by Iran and six world powers, including the United States.
The Israeli leader claims the deal will not prevent Tehran from being able to build an atomic bomb.
Iranian Foreign Minister Mohammad Javad Zarif said Netanyahu was "scaremongering" but would not be able to prevent the deal from being reached with the United States, Britain, France, Russia, China, plus Germany.
Negotiators hope to reach a partial agreement by March 31 t that curbs Iran's uranium-enrichment activity in exchange for relief from economic sanctions.
A deadline to reach a final agreement has been set for June 30.