The United States sought Iran's help to bring Yemen's warring parties into talks on a political settlement when U.S. and Iranian foreign ministers met on April 27, U.S. officials say.
Iran is allied with the Huthi militias that took the Yemeni capital Sanaa in September, demanding a more inclusive government.
The Shi'ite Huthis have since swept south, unsettling Sunni-ruled Saudi Arabia, which has led a deadly bombing campaign against them.
A U.S. State Department spokesman confirmed that Secretary of State John Kerry had asked Iranian Foreign Minister Mohammad Javad Zarif to use Tehran's influence to get all sides into talks.
An anonymous U.S. official specified that this meant seeking Iranian help to get the Huthis to negotiate.
Kerry, speaking before his meeting with Zarif on April 27, told reporters that he expected Yemen to attend talks.
Based on reporting by Reuters