Under Secretary for Political Affairs William J. Burns is leading the U.S. delegation as it joins the P5+1 partners as well as Iranian representatives in talks beginning in Istanbul, Turkey.

“We seek to launch a meaningful and practical process that addresses the core issues with Iran's nuclear program,” U.S. State Department spokesman Philip Crowley told a daily press briefing.

“As the P5+1 has consistently made clear, we are committed to holding Iran accountable to its international obligations, and will continue to do so until Iran takes tangible steps to resolve international concerns with its nuclear program,” he said.