Limited progress is expected in the separate meetings taking place on Wednesday in Vienna and Istanbul.

Bill introduced by bipartisan group of lawmakers is latest congressional effort to slow development of the Islamic Republic's disputed nuclear program.

Iranian envoy urges world powers to take a less confrontational approach in talks on its atom program, positing that extensive economic sanctions are bound to fail.

Maj. Gen. (ret.) Amos Yadlin says 'We are headed toward a collision course by the end of this year,' adding that Israel is capable of attacking Iran on its own.

Kim Jong-un's threats of nuclear annihilation can be chalked up to a lot of chatter and very little substance, but consider how the same threats could sound if coming from Iran. Such a reality is fast approaching.

Resolution 65 goes beyond affirming U.S. commitment to preventing a nuclear Iran to ensure it will 'authorize the use of military force, diplomatic, military, and economic support to Israel in its defense of its territory, people, and existence.'

Head of Iran's Atomic Energy Organization says 'for now we have no plans for enrichment above 20 percent' but may need fuel enriched to 45 to 56 percent in the future.

When it comes to the Islamic regime, time is short and the window of opportunity is closing. The longer we look for compromise, the more leverage they have against us.

Western diplomats describe first day of talks as disappointing and difficult, leaving little hope of striking a quick deal in dispute over Iran's nuclear program.

Western diplomats express disappointment over Iranian officials' refusal to respond to a P5+1 proposal that would restrict the Islamic republic's uranium enrichment in exchange for modest relief from sanctions; talks to renew Saturday.