Washington-Sen. Bob Casey, D-Pa., is on a crusade to stem the flow of ammonium nitrate into Afghanistan, where it has become the biggest killer of U.S. troops as the key ingredient in improvised explosive devices. “I cannot overemphasize the urgency of this issue,” Casey declared recently. “Pakistan’s leaders must do everything in their power to ensure that ammonium nitrate and other precursor ingredients are well regulated in Pakistan and not transported into Afghanistan for illicit use.” In January 2010, the Afghan government banned the use of and manufacture of ammonium nitrate as a fertilizer. However, according to Casey, ammonium nitrate continues to flow into Afghanistan from Pakistan, Central Asian countries, and Iran. Earlier this year, Casey worked with his colleagues on the Senate Appropriations Committee to include language in the foreign operations appropriations bill that would direct the Secretary of State to submit a report detailing steps taken by the U.S. government to help stem the proliferation and transport of ammonium nitrate into Afghanistan. Senator Casey also sponsored a resolution which passed the Senate that called for increased support to combat ammonium nitrate and an increased effort and focus by the governments of Pakistan, Afghanistan, and Central Asian countries to effectively monitor and regulate the manufacture, sale, transport, and use of ammonium nitrate fertilizer.