This notion of state responsibility for the September 1999 apartment bombings is baloney. There was a very clear sequence of events in that summer. When NATO's squalid bombing of Kosovo was brought to an end by Russian (and other) efforts to mediate, Chechnya's gangsters in their autonomous republic, which Yeltsin conceded to them in 1996 after they had laid siege to a maternity hospital (you couldn't make it up), mistook Russia's restraint from starting WW3 for weakness, and invaded neighbouring Dagestan. They were very swiftly driven back by the Russian army. Stung however, Chechen thugs decided to blow up apartment buildings in Moscow and elsewhere, in revenge. Unsurprisingly, this irrevocably changed Moscow's hitherto lenient attitude and tanks were sent back to Grozny. After the attempt by Chechens to gain political capital from the threat of blowing up innocent schoolchildren in Beslan in 2004, it might have been assumed that the conspiracy theories about the Moscow apartment bombings would die out completely.
Self-evidently, regardless of whatever dubious agenda these anonymous ‘sources’ may be trying to tout, this is worthless tittle-tattle.