Yet it was by no means a simple act of revenge, say Speckhard and other experts, insisting it is wrong to imagine the Black Widows as loyal widows seeking justice. (Sharipova's husband is believed to still be alive.) The women are in reality the products of a sophisticated process of indoctrination with deep roots in the North Caucasus, where a less conservative form of Islam has meant insurgents have few qualms about using women in their attacks. "The women who take part in terrorism do it not out of their own desire or willingness but because they are manipulated. They are given no other choice," says Yulia Yuzik, who has interviewed scores of Black Widows and their relatives in the Caucasus for her book Nevesty Allakhy (Brides of Allah).

Yuzik says the recruitment process usually begins when a loved one collaborates with insurgents and then gets killed or persecuted by Russian forces. The family is often ostracized by other members of their community, who are desperate to avoid persecution themselves, Yuzik says. "The community that welcomes you after that is the Islamist one. There you find self-respect. You are called a sister. You go to pray with them, socialize with them, and you integrate into these groups based around Islam. That in itself serves as a kind of counterforce to the security regime, a way of expressing grief and frustration."

...The ease of finding such women over the Internet, and their usefulness to terrorist groups, suggest that the role of women in jihadist movements will continue to grow. Even ultraconservative groups like al-Qaeda, which had long avoided recruiting women, have come around to the tactic, says Mia Bloom, author of Bombshell: Women and Terror. In Russia the problem is particularly acute, as more than 50% of the country's suicide attacks have been committed by women, compared with about 30% globally.

1. Russia: Suicide Bomber was Chechen's terrorist widow.
2. Russia: Second Moscow bomber was a teacher.
3. Russia: "inadmisible to link Islam to terrorism", mufties say.