Laborers pose with handfuls of the fertilizer ammonium nitrate which fell to the ground as they were unloading bagfuls of it from a truck in Multan December 15, 2011. U.S. lawmakers are ready to freeze up to $700 million in aid to Pakistan until Congress gets assurances that Islamabad is helping fight the spread of homemade bombs in the region, a move one Pakistani senator called unwise and likely to strain ties further. U.S. lawmakers said many Afghan bombs are made using using ammonium nitrate, a common fertilizer smuggled by militants across the border from Pakistan into Afghanistan. REUTERS/Akhtar Soomro (PAKISTAN - Tags: ENVIRONMENT BUSINESS CONFLICT PORTRAIT AGRICULTURE) - GM1E7CG021501
