Chechen rebel leader Doku Umarov's declaration that he ordered the Moscow Metro bombings has again raised questions over the Kremlin's "Chechenisation" policy, the term often given by analysts to Moscow's partial transfer of control over the republic to local allies.
Ramzan Kadyrov, the controversial ex-rebel who has enjoyed Moscow's backing since coming to power as Chechen president in 2007, condemned the bombers in language similar to Russian Prime Minister Vladimir Putin's pledge to "scrape them off the bottom of the sewer".
"Terrorists should be sought out and found in their lairs," he wrote in an opinion piece published by Russia's Izvestia newspaper.
"They should be poisoned like rats, crushed and destroyed."
In his fierce declaration of loyalty to the Russian state, apparently written before Mr Umarov's statement, Mr Kadyrov was careful to say he did not want to speculate about where the trail might lead. He preferred, he said, to wait for Russian federal investigators to do their work.
In the same breath, Mr Kadyrov praised Russia's secret service for the recent killing in Ingushetia of leading Islamist militant Alexander Tikhomirov (aka Said Buryatsky), an ethnic Russian convert to Islam who is said to have been an associate of Mr Umarov.
Mr Umarov is a much bigger target for Russian federal security forces. His separatist pedigree includes serving as security minister from 1996-99, when the republic had de facto independence from Russia.
Whether or not Moscow's response to the bombings inadvertently provokes new unrest in Chechnya comes down in part to Mr Kadyrov's ability to make good his claim to be in control there, and the Kremlin's reluctance to admit otherwise.
But the men running the Kremlin arguably face an enemy much more elusive than the rebels of the past.
"A consequence of Chechenisation has been a consolidation of the Islamists' status as the vanguard of regional opposition to Moscow," says Will Hartley, editor of Jane's Terrorism and Insurgency Centre.
Doku Umarov's whereabouts are anyone's guess but "it would be a surprise if he were outside the North Caucasus region", Mr Hartley adds.
"The insurgency is particularly strong in Ingushetia and Dagestan, making these territories credible locations, but equally he may be operating out of one of the quieter republics where the Islamists have a presence, such as Kabardino-Balkaria," Mr Hartley points out.
Russia expert Professor Anatol Lieven, of King's College London, notes that other Chechen rebel leaders have operated from outside the former Soviet Union.
If Mr Umarov is somewhere inside the mainly Muslim parts of the Russian North Caucasus, the professor says, he is not necessarily hiding out in the region's famously remote mountains.
"The region's cities, where there is a population willing to provide shelter, are equally good," he says. "The key is not terrain, it's people."
If Doku Umarov is inside Chechnya itself, he faces considerable risks.
"Under Putin's Chechenisation policy, Kadyrov has been allowed to establish complete personal control over Chechnya in return for restoring law and order and re-establishing Moscow's writ over the territory," says Mr Hartley.
"Investing a local strongman with unity of command has been instrumental in suppressing the long-running insurgency, which today - within Chechnya at least - no longer poses a significant or credible threat."
Mr Kadyrov denies accusations that his followers within Chechnya are behind many of the extrajudicial killings, abductions and other crimes witnessed there since the last war but campaigners argue that Chechenisation has taken a heavy toll on human rights.
There are limits, however, to Mr Kadyrov's power, dependent as it is on the acquiescence of other former rebels.
"Clearly he does not have enough ability to suppress militancy altogether but then very few places in the Muslim world can control militancy completely," says Prof Lieven.
Anna Matveeva, a researcher at the London School of Economics, says that the fact Mr Kadyrov has "more control of Chechnya than all of his predecessors is not a small achievement".
To say the Moscow bombings are proof that Chechenisation has failed would be like arguing that the 2005 suicide attacks on London's transport network are evidence of the failure of British government policy towards its Muslim community, Prof Lieven argues.
"Does that show British policy has failed?" he asks. "It just shows how difficult an issue it is."
On a recent visit to the Chechen capital Grozny, the King's College academic met a Western journalist who, he says, remarked on the impressive rebuilding work accomplished since the last war, and bemoaned the state of the Afghan capital Kabul by comparison.
Since the last Chechen war, the Kremlin has pumped money into the North Caucasus to buy the loyalty of local clans, Professor Pavel Baev of Oslo's International Peace Research Institute told BBC World Service.
"Buying stability there is no longer possible because the price keeps going up," he said. "Crisis is crisis and there is only that much money you can give away."
Asked if the Russian public would regard the Moscow bombings as a failure of government, he said: "I think [for them] it is a very certain awakening that the problem is not solved.
"After all these years of instability, after all the declarations that we have achieved our victory in that particular war on terror, it comes back."
According to Mr Hartley, Chechenisation has been a success for the Kremlin in some senses.
"It achieved the objectives of suppressing the insurgency and restoring its writ while dramatically reducing the punitive cost - in terms of blood, treasure and political capital - that Moscow had been forced to expend since the outbreak of the first Chechen War in 1994," he says.
But, the Jane's editor adds, what made the policy possible in the first place was the emergence of a cleavage within the insurgency between secular nationalists such as Mr Kadyrov, and militant Islamists today embodied in Doku Umarov.
"The policy has not addressed any of the underlying socioeconomic and political causes of the region's instability, and thus to a certain extent the instability has simply been displaced to the rest of the North Caucasus region, particularly Ingushetia and Dagestan," he says.
"The recent Moscow subway attacks, on top of the escalating violence within the region itself, are dramatic evidence that the current manifestation of the insurgency has as much potential to trouble Moscow as the previous Chechen-centric insurgency."