Iran has until March to begin cooperating with the International Atomic Energy Agency's probe into the country's nuclear program, a U.S. official said. Iran has repeatedly denied it is pursuing the development of nuclear weapons. "If by March Iran has not begun substantive cooperation with the IAEA, the United States will work with other board members to pursue appropriate board action, and would urge the board to consider reporting this lack of progress to the U.N. Security Council," said U.S. diplomat Robert Wood.