The United States will buy heavy water from Iran's nuclear program, and expects it to be delivered within weeks, US officials said on Friday, a move that was quickly criticized by Republican lawmakers.The US Department of Energy will buy 32 metric tons of heavy water from Iran's nuclear program worth $8.6 million, a department spokeswoman said. Heavy water is an important component in the development of nuclear weapons. "The United States will not be Iran's customer forever," the spokeswoman said. The department expects to resell the purchased heavy water to domestic commercial and research buyers, including a national lab.Iran's compliance with last year's landmark nuclear agreement with the United States and other world powers meant that the heavy water had already been removed from Iran, ensuring that it would not be used to support the development of a nuclear weapon, State Department spokesman John Kirby said."Our purchase of the heavy water means that it will instead be used for critically important research and non-nuclear industrial requirements," Kirby added. The purchase, first reported by the Wall Street Journal, was slammed by Speaker of the House Paul Ryan, a Republican. He said in a statement it appeared to be part of the Democratic administration's efforts to sweeten the nuclear deal with Iran and would "directly subsidize Iran's nuclear program."