Russia's most wanted militant has vowed to bring "a year of blood and tears" to the country, in a video where he appears flanked by a man resembling the main suspect in last month's Moscow airport bombing.
In the clip uploaded to a rebel website over the weekend, Doku Umarov – the self-styled "Emir of the Caucasus" and the leader of the Islamic insurgency in the country's south – was flanked by two men, one of whom is believed to be the suicide bomber who attacked Domodedovo airport.
Umarov does not mention the airport bombing in the undated video, which appears to have been made before the attack. He introduces a man standing on his left as "Seifullah" and says he is being sent to Moscow to carry out a "special operation".
Russian media believe the man in the video could be Magomed Yevloyev, 20, from the troubled republic of Ingushetia, which borders Chechnya. Russian security agencies have said the bomber was a 20-year-old native of the North Caucasus whose identity was already known, but refused to officially release the name while investigations were ongoing.
However, media outlets known to be close to the FSB security service have named the bomber as Yevloyev, and the figure in this weekend's video bears a striking resemblance to a widely-circulated photograph of the young man. Yevloyev, whose father is a bus driver and whose mother works as a school teacher, left his home in the village of Ali-Yurt in Ingushetia last summer, supposedly in search of work.
Instead, it appears he began a path which would lead him to blow himself up in the arrivals hall of Domodedovo airport a fortnight ago, killing 36 people and wounding 180. Eight foreigners, including one Briton, were among those killed.
Last week, Alexander Bortnikov, the head of the FSB, told President Dmitry Medvedev that a "huge amount of highly powerful drugs and psychotropic substances" had been found in the bomber's body. Since the attack both Mr Medvedev and Prime Minister Vladimir Putin have spoken in uncompromising terms about the need to "liquidate" terrorists, but the video will be worrying for Russia's rulers, who have staked their reputations on pacifying the North Caucasus.
"Depending on the reaction, depending on your actions, God willing, these operations will be conducted monthly, weekly, as God allows us," Umarov says in the video. The chilling 12-minute recording is shot in a small, enclosed space, and the three men are dressed in combat fatigues, positioned below a black flag with an Arabic inscription.
Umarov, speaking in heavily accented Russian, says he is at a base of the "Riyadus Salikhin brigade of martyrs", a terrorist division that has taken responsibility for previous attacks.
"I have made a long journey to come here and see these brothers," he says. "I have made a long journey so our brothers can carry out a special operation... in the capital of Russia.
"It is through our actions that we are having to wake you up," he says, addressing the Russian people. "If this is too little for you, then, God willing, other strikes will follow, too. I can tell you with 100 per cent confidence that if there is God's will for it... we will make this year a year of blood and tears."
The young man on Umarov's left, who may well be the Moscow airport bomber Yevloyev, speaks at the end of the video. He talks quietly, stumbling over his words and with his face bathed in an eerie white light, saying he has accepted the task of carrying out an attack. "Other brothers will come after me to give their lives for God," he says. "These are my last words."
According to Russian security sources, police are hunting for two accomplices of Yevloyev, whom they believe helped co-ordinate the attack and are still at large. These are his brother, Islam Yevloyev, and Adam Ganizhev, also from Ali-Yurt in Ingushetia.
The Russian website Life News interviewed Ganizhev's father Magomed, who said his son disappeared on 31 August last year, dressed in light clothes and with just 80 roubles (£1.60) in his wallet. "Since then we have heard nothing about him," said the father, adding that the family had informed local police and government officials about their son's disappearance.
'The emir of the caucasus'
* Doku Umarov is Russia's most notorious terrorist and the nominal leader of the insurgency that spans the south of Russia. Believed to be continually on the move in the mountainous terrain of Chechnya, Ingushetia and Dagestan, he has eluded capture or death despite the best attempts of the Russian army and security services.
* Umarov took up the leadership of the insurgency after several other leaders were killed in 2005 and 2006, notably Shamil Basayev, who masterminded the Beslan school siege, and Aslan Maskhadov, who was President of Chechnya when it was a de facto independent state in the late 1990s.
* Born in Chechnya in 1964, Umarov studied engineering at Grozny University, but went on to become a rebel fighter in both Chechen wars. He has been a fighter in the terrorist underground since the end of the second Chechen war when Moscow took back control of the territory, and there are rumours that he personally took part in the Beslan school siege.
* As the local Kremlin-backed strongman Ramzan Kadyrov has rebuilt Chechnya, Umarov has moved the insurgency's goals away from secular Chechen nationalism towards a more overarching Islamist rhetoric. Widespread unemployment, police brutality and official corruption in the republics of the North Caucasus act as recruiting sergeants for Umarov's cause. Militants now come not only from Chechnya but from across the region.
* Experts believe that the insurgents no longer have the capacity to carry out large-scale terrorist attacks such as the Moscow theatre siege in 2002 or Beslan. However there are almost daily attacks on police and other officials in the North Caucasus itself, and the Domodedovo bombing shows that they can still mount isolated suicide attacks in the Russian capital.
* Recently, there have been rumours that Umarov is critically ill, and that other rebel leaders have sought to depose him. But if this weekend's video, which ends with Umarov embracing the man he is sending on a "special operation", does indeed turn out to show the Moscow airport bomber, it will prove that Umarov is still at the centre of things and able to oversee such attacks personally.