Iran nuclear deal hits milestone aimed at sanctions relief

The U.S. expects Iran will take months to live up to its end of a seven-nation nuclear pact that could eventually provide the country relief from international sanctions.

The deal was formally taking effect Sunday, opening the way for Iran to make major changes to an underground nuclear facility, a heavy water reactor and a site for enriching uranium. The changes will not happen immediately, and Iran must further constrain its nuclear program before relief from sanctions will occur.

Senior administration officials said Saturday they understand it's in Iran's best...