U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Jawad Zarif met here on Thursday, a senior State Department official said, the latest in an intensifying series of talks to reach a deal on Iran's disputed nuclear program. There was no immediate word on whether the two men had made progress in the hour-long session on a deal to curb Iran's nuclear work in return for an unraveling of Western economic sanctions on Tehran. Meanwhile, Zarif, speaking on a panel at the World Economic Forum in Davos, warned that more sanctions by the U.S. Congress would kill the negotiating process between Iran and major powers on its nuclear program.