Negotiators from Iran and a group of world powers are meeting Tuesday in Vienna to discuss a long-term agreement to ensure Iran's nuclear program is peaceful.
The two sides reached an interim deal in November that calls for Iran to cut back its most sensitive nuclear activity in exchange for limited sanctions relief.
Iran has long insisted that its nuclear program is only meant for things like generating power and medical research.
In the new agreement, the group that includes the United States, Britain, China, France, Russia and Germany wants Iran to provide assurances it will not develop nuclear weapons. In return, Iran wants all of the sanctions that have sharply affected its economy to be lifted.
Ahead of the talks, Iranian Foreign Minister Javad Zarif held a meeting Monday night with European Union foreign policy chief Catherine Ashton, who leads the negotiations for the world powers.
Also Monday, Iranian Supreme Leader Ayatollah Ali Khamenei said the talks will "lead nowhere," but he does not oppose them.