From the article:

Earlier, a website known for militant Muslim comment published a claim of responsibility for the crashes of two Russian airliners, connecting the action to Russia's fight against separatists in Chechnya.

The statement was signed "the Islambouli Brigades." A group with a similar name has claimed responsibility for at least one other attack, but the authenticity of the statement could not immediately be confirmed.

A spokesman for the Federal Security Service said he could not immediately comment on the Web site's statement.

Russian officials have repeatedly contended that the rebels who have been fighting Russian forces in Chechnya for nearly five years receive help from foreign terrorist organizations, including al-Qaeda.

The claim did not refer to al-Qaeda, but a group called "the Islambouli Brigades of al-Qaeda" claimed responsibility for last month's attempt to assassinate Pakistan's prime minister-designate.

It pays to read the links.