The United States secretly shipped out of Iraq more than 500 tons of low-grade uranium dating back to the Saddam Hussein era, the Pentagon said Monday. The U.S. military spent $70 million ensuring the safe transportation of 550 metric tons of the uranium from Iraq to Canada, said Pentagon spokesman Brian Whitman. The shipment, which until recently was kept secret, involved a U.S. truck convoy, 37 cargo flights out of Baghdad to a transitional location, and then a transoceanic voyage on board a U.S.-government-owned ship designed to carry troops to a war zone, he said. The “yellowcake” uranium transfer was requested by the Iraqi government at the encouragement of the U.S. government, Whitman said. The United States approached Canadian company Cameco to bid for the material, according Cameco spokesman Lyle Krahn. He would not disclose the winning bid amount.