Russia's top Islamist leader Doku Umarov called in a video released on Wednesday for jihadists to stage attacks against a range of targets that include the 2014 Sochi Olympic Games.
"We know that on the bones of our ancestors, on the bones of many, many Muslims who died and are buried on our territory along the Black Sea, today they plan to stage the Olympic Games. We, as the Mujahedeen, must not allow this to happen by any means possible," Umarov said in a message posted on the kavkazcenter.com website.
Russia hopes to make the 2014 Winter Olympic Games into a showcase event that highlights the economic and social strides that the country has made under President Vladimir Putin.
But the Black Sea resort is located in the immediate proximity of Russia's North Caucasus -- an extremely volatile region that has witnessed two post-Soviet wars in Chechnya and daily violence in republics such as Dagestan.
The Russian authorities ordered tougher security for Sochi after the April Boston Marathon bombings that were blamed on two ethnic Chechen brothers who spent parts of their lives in Russia.
In his comments, Umarov appeared to be referring to the deportation of ethnic tribes living on the Black Sea coast and mountains of the Sochi area by the 19th century tsarist army, after Russia's protracted campaign to pacify the Caucasus, also known as the Caucasus War.
That war ended with a grandiose May 1864 parade in Sochi's Krasnaya Polyana, now the site of a massive development of mountain ski resorts. Russia's hosting of the Winter Olympic Games would therefore fall during the 150th-year anniversary of the natives' defeat.
The area's inhabitants, sometimes warring tribes that attempted to unite against the Russians, are known as the Circassians.
Following Russia's victory, they were deported en masse to Muslim countries across the Black Sea, notably Turkey. Many today believe this was an act of genocide, due to the huge humanitarian toll.
Circassians in Russia inhabit mostly the North Caucasus regions of Adygea, Kabardino-Balkaria and Karachayevo-Cherkessia, but some have remained in the northernmost districts of Sochi. They have put up only mild protests against the Games, unlike the diaspora.
Putin last month expressed concern that militants "constantly trickle to the Caucasus from Georgian territory" and Russian special forces have crossed the border to attack them.
In May 2012, Russia said it had foiled Umarov's attack plot against Sochi and uncovered a cache of weapons in Georgia's breakaway region of Abkhazia, whose border is just a few kilometres away from the main Olympic stadiums.
Umarov for his part has been viewed as Moscow's enemy number one since he took charge of the loose band of guerrillas who continue to stage attacks against Russians targets and fight federal troops in periodic skirmishes.
The bearded guerrilla has been pronounced dead by the Russian authorities on many occasions only to resurface again in videos that claim particularly brutal attacks.
In the latest clip he and two other men appear in camouflage in a wooded area, and birds are heard loudly chirping in the background.
Umarov has assumed responsibility for strikes such as the 2010 Moscow metro bombings that killed more than 40 people and the 2011 Domodedovo airport attack in the capital in which 37 people died.
He argued in the video that his earlier call for a truce was interpreted by the Russian authorities as a sign of weakness.
"Today we must prove to those in the Kremlin that our good will is not our weakness," he said.
"For this reason, I call on each of you... on the territory of the Caucasus to do your utmost... to prevent these satanic dances on our bones," he said in reference to the Sochi Games.