Knocking on door after door, thousands of volunteers fan out every month across southern and eastern Afghanistan, vaccinating children against polio, a disease eradicated almost everywhere else in the world.
Usually, the volunteers -- sent by the government and sponsored by United Nations agencies -- bring a single-page letter requesting people to cooperate, "for the benefit of our next generations." The letter's signatory: Mullah Mohammad Omar, the one-eyed supreme leader of the Taliban.
"We always carry a copy," says Dr. Attar Wafa, the chief of polio vaccinations in the insurgent-infested province of Laghman, much of which is a no-go area for government workers and foreigners.
The antipolio campaign brings together the Taliban, President Hamid Karzai's central government, Unicef and the World Health Organization in an uneasy but functioning partnership -- one that recognizes the reality of the insurgents' stranglehold over large chunks of the country.