No one remembers Hasna Maryi ever opening her family's Koran. She rarely attended her village mosque, and she told others she regarded the imam, who once made a pass at her, as a lecherous scoundrel. It was not religious extremism that made this villager from Anbar province blow herself up at an Iraqi-police checkpoint last summer, killing three officers and injuring at least 10 civilians.
Religion may not have been her motive, but Hasna was an early, willing casualty of the latest jihadi trend: the use of women on the front lines of the holy war. American and Iraqi officials say...