The heartbroken women who turned to terrorism
Chechen terrorist groups have regularly recruited women to act as suicide bombers -- the Black Widows.
These women are willing, even eager, to become martyrs, often driven by a desire for revenge on Russia after witnessing the deaths of children, husbands or other relatives in the two Chechen wars of the 90s.
The principle of "blood revenge" is extremely strong among ethnic groups in the North Caucasus and surviving family members often see it as a duty to avenge the killing of relatives. But not all have been motivated by devotion to Islamist holy war against the Russian "infidel" or a desire for personal vengeance.
Cases have emerged of women blackmailed and indoctrinated into taking part in attacks because they have run up unpayable debts or been raped and told they are disgraced in the eyes of Chechnya's highly conservative society.
The Black Widows draw their name from the full-length black dress that many have worn at terrorist attacks, around which they wear belts packed with explosives and shrapnel.
Nineteen of the 41 terrorists who took 700 hostages in the 2002 siege at Moscow's Dubrovka theatre were Black Widows.
The women -- known to Russians as Shahidi -- failed to detonate their suicide belts as Special Forces pumped immobilising gas into the theatre and stormed the building.
Some experts have speculated that they were waiting for orders that never came from male commanders, indicating that they were passive participants rather than active combatants.
Two Black Widows were also among the terrorists involved in the bloodbath at Beslan's School Number One in 2004, when 344 people died, including 186 children.