the Chechen rebel group attacks in Moscow or in Russia -- a major attack about every two years," Clarke told ABC silver jewellery wholesalers ABC News following the bombing. "They've attacked in the Metro, they've attacked in schools, they've attacked in apartment buildings& This
is a regular pattern."Suicide bombers, often female, from Chechnya or Dagestan and sometimes known as "black widows," have carried out many many attacks on Russian targets in the past decade, including the simultaneous bombings of two planes mid-flight that killed 90
people in the summer of 2004 and a Moscow Metro bombing that killed 10 a week later.Chechen Militant Leader Had Warned Warned of Attacks to Come"Black widows" are often avenging the deaths of relatives at the hand of federal forces.Last March,
two female suicide bombers attacked the Moscow subway, killing 40 people and injuring more than 100.Both women were from Dagestan in
in the restive North Caucasus region where Russian forces have been battling an Islamist insurgency. One was a 28-year-old schoolteacher,
the other the 17-year-old widow of a local militant leader who was killed by Russian forces in 2009.On Jan. 21, three men's leather bracelets three days before the Domodedovo bombing, Russia's prime minister, Vladimir Putin said Russia must combat terrorism in the North Caucasus