A new Pentagon report highlights a notable trend: Expanded military operations and counternarcotics raids in southern Afghanistan have helped to decrease the cultivation of drugs used to fund the insurgency there. The decrease was the most striking in areas where coalition forces have a strong presence, particularly in Helmand province, said the “Report on Progress Toward Security and Stability in Afghanistan.” Nearly 20,000 Marines are deployed there as part of a 30,000-troop coalition force commanded by Maj. Gen. John Toolan, head of II Marine Expeditionary Force (Forward) and Regional Command-Southwest. A version of the report is released every six months,…