WASHINGTON, July 11 -- Aggressive Hydraulics Inc., East Bethel, Minnesota, has submitted a letter to the U.S. Department of Commerce Bureau of Industry and Security underscoring the national security implications of increasing imports of these steel derivative articles. The company argues that the domestic industry's contraction and reliance on foreign supply pose a threat to critical sectors. Aggressive Hydraulics manufactures finished hydraulic cylinders, which are composed primarily of steel more ST