Difficulty with striking an appropriate balance between national security and export competitiveness has made the subject of export controls controversial for decades. Through the Arms Export Control Act (AECA), the International Emergency Economic Powers Act (IEEPA), the Export Controls Act of 2018 (ECA), and other authorities, the United States restricts the export of defense articles; dual-use goods and technology; certain nuclear materials and technology; and items that would assist in the proliferation of nuclear, chemical, and biological weapons or the missile technology used to deliver them. U.S. export controls are also used to restrict exports to certain countries on which the United States imposes economic sanctions.