The materials in question are almost certainly two short video clips posted on kavkazcenter.com on August 1. In one, Umarov announces that he is stepping down as North Caucasus emir because he is "tired." He said that decision was reached unanimously by the commanders of the various Chechnya-based fighting units. Umarov appeals to the heads of the Kabardino-Balkar-Karachai, Daghestan and Ingush jamaats to pledge loyalty to his chosen successor, Aslambek Vadalov. Footage shot in June in which Umarov formally designates Vadalov his deputy (and thus his successor in the event of his death) was posted on kavkazcenter.com on July 24.
In the second clip, three Chechnya-based field commanders -- Tarkhan (an Ingush), Mukhannad (an Arab), and Khusein Gakayev (a Chechen whom Umarov named commander of the Chechnya-based forces the same day he named Vadalov his deputy) expressed their support for Vadalov, whom they described as "reliable" and "God-fearing."
Two years earlier, Udugov incurred the wrath of Akhmed Zakayev, the London-based head of the Chechen Republic Ichkeria government in exile, by rejecting the concept of an independent Chechen state in favor of an Islamic state encompassing the entire North Caucasus.
Zakayev has consistently claimed that Russia's Federal Security Service (FSB) suborned Udugov, who pressured Umarov to abjure the concept of Chechen independence and embrace the cause of jihad in the name of a North Caucasus Islamic state. The FSB rationale, according to Zakayev, was to give the Kremlin free rein to deploy more forces to the North Caucasus under the pretext of fighting "terrorism" in order to wipe out the resistance and deal the death blow to the cause of an independent Chechnya.
Scapegoat, Or Turncoat
Umarov's announcement that he was handing over the leadership to Vadalov was widely interpreted as reflecting disagreement within the insurgency ranks. But opinions differed over whether that disagreement focused on military tactics or ideology.
Zakayev told RFE/RL's North Caucasus Service on August 2 that Vadalov and the younger generation of commanders consider Umarov, and the emirate he claims to head, compromised in light of the persistent allegations that Umarov was being manipulated, through Udugov, by the FSB. Zakayev suggested that they may therefore have pressured Umarov to cede the leadership, but in such a way as to preserve the illusion of ideological unity.
One day later, Zakayev told Reuters that Vadalov was not an Islamic radical, and hinted that he might be amenable to peace talks with Moscow. That statement is, however, at odds with the characterizations of Vadalov by his fellow commanders, and with his own professed commitment to the "jihad" against Russia.
Umarov's subsequent U-turn was widely construed as substantiating the hypothesis of a rift within the insurgency. But it still remained unclear whether Umarov's original "resignation" was voluntary, and he reconsidered it in light of subsequent developments (possibly after fighting units elsewhere in the North Caucasus refused to accept Vadalov as their leader), or involuntary, and he had succeeded in reasserting control.
As for today's statement, it is equally unclear whether Umarov is seeking to offload onto Udugov responsibility for a U-turn that has damaged his credibility, or, assuming that Zakayev's claims of Udugov's complicity with the FSB are true, Umarov has decided to sever all ties with Udugov.