KABUL, Afghanistan - U.S. Marines and Afghan forces have destroyed hundreds of tons of poppy seeds, opium, and heroin in southern Afghanistan this month in raids that a top American official said showed the new U.S. anti-narcotics strategy in Afghanistan was working.

U.S. and NATO troops are attacking drug warehouses in Afghanistan for the first time this year to counter the country's booming opium poppy and heroin trade. NATO defense ministers approved the targeted raids late last year, saying the link between Taliban insurgents and drug barons was clear. U.N. officials say Taliban fighters reap hundreds of millions of dollars from the drug trade each year.

The United States announced last month that it would no longer support the destruction of farmers' poppy plants, which it had done for years without ever eradicating a significant portion of the crops, and, instead, would increase attacks on warehouses controlled by drug lords.

Marines, British troops, and Afghan forces supported by the U.S. Drug Enforcement Administration have increasingly targeted drug warehouses in Helmand and Kandahar provinces, the largest opium-poppy-growing region in the world.

The new strategy is "a historic change if it's successful, and the first indications were very, very promising," said Richard Holbrooke, President Obama's envoy for Afghanistan and Pakistan.

Seizures this summer illustrate the huge quantities of drugs the military can destroy. Marines in Helmand working with DEA-mentored Afghan police seized 297 tons of poppy seeds, 77 pounds of heroin, and 300 pounds of opium in raids in mid-July. About 1,200 pounds of hashish and 4,225 gallons of chemicals used to convert opium to heroin were also seized.

Bomb-making materials, rocket-propelled grenades, and AK-47s were also seized, underscoring what the U.S. Embassy said was "the connection between drug trafficking and the insurgency."

On the battlefront, a U.S. service member died during a clash with insurgents in the south, the U.S. military said yesterday, bringing to at least 39 the number of U.S. troops killed this month. July has been the deadliest month for U.S. and NATO forces in the Afghan war.

Also yesterday, one of President Hamid Karzai's vice presidential running mates in next month's election escaped injury when his convoy came under fire in northern Afghanistan. Militants opened fire on Mohammad Qasim Fahim as he traveled from Kunduz to Takhar province.