The Iranian Foreign Ministry stressed on Monday that the country's right to enrich uranium domestically and the removal of sanctions are nonnegotiable.

MUSCAT, Oman —Iran and the United States held their first technical-level talks on Tehran’s rapidly advancing nuclear program Saturday, a more complex phase of their high-stakes negotiations.

The talks seek to limit Iran's nuclear program in exchange for the lifting of some of the crushing economic sanctions the U.S. has imposed on the Islamic Republic.