For one, the United States doesn’t actually produce all that much uranium (about 2 percent in 2015) and is actually a net importer of the chemical, according to Jeffrey Lewis, a nuclear nonproliferation expert at Middlebury Institute and former director at the New America Foundation.
For another, Russia doesn’t have the licenses to export uranium outside the United States, Oilprice.org pointed out, "so it’s somewhat disingenuous to say this uranium is now Russia’s, to do with what it pleases." The Kremlin was likely more interested in Uranium One’s assets in Kazakhstan, the world’s largest producer.
Trump is also wrong that Clinton alone allowed the transfer.
The Kremlin’s 2010 purchase of a controlling stake in Uranium One had to be approved by the nine members of the Committee on Foreign Investment in the United States.
That included Clinton as secretary of state, but also the secretaries of the Treasury (the chairman of the committee), Defense, Justice, Commerce, Energy and Homeland Security as well as the the heads of the Office of the U.S. Trade Representative and the Office of Science and Technology Policy. The deal also had to be okayed by the independent Nuclear Regulatory Commission as well as Utah’s nuclear regulator.