guns, many of them exported legally, are flowing into Latin America in an “iron river” ending in the hands of drug cartels and abusive security forces, activists said Monday, calling for greater oversight from U. John Lindsay-Poland, an activist from Stop US Arms to Mexico, added that lax license rules and enforcement helped facilitate the cross-border flow of arms — including military-grade weapons desired by cartels. gunmakers have maintained that they sell firearms legally to Americans who pass a background check, and their lawyers have argued that holding them responsible opens the door for other lawsuits, such as the deaths of Russians killed by their weapons in Ukraine