MOSCOW - President Vladimir Putin has imposed the Kremlin's writ on every corner of Russia except one: the Chechnya region, whose leader, Ramzan Kadyrov, often pays little heed to the rules that govern the rest of the country.
Putin is now trying to rein Kadyrov in, though alienating him would risk reigniting an Islamist insurgency that he helped the Kremlin leader defeat.
A former Islamist rebel who has ruled the turbulent, mainly Muslim region in Russia's North Caucasus since 2007, Kadyrov swears loyalty to Putin.
Those public expressions have helped Putin turn a blind eye to Kadyrov's idiosyncrasies, which include enforcing a strict Islamic "code of virtue," embarrassing the Kremlin with verbal attacks on opposition politicians, and employing methods against insurgents that human rights groups see as rights abuses.
But he is widely reported to have opponents in the Kremlin and an opportunity has presented itself to put him in his place: The 39-year-old Chechen leader's term in office runs out in April, and he needs Putin's approval to stay on.
"For too long, the argument goes, Kadyrov has been allowed to run things his own way," said Alexander Baunov of the Carnegie Moscow Center think tank. "Moscow's elite have been increasingly looking to subordinate Chechnya to Putin."
Asked in February what would happen to Kadyrov when his term expired, Kremlin spokesman Dmitry Peskov said it was up to the president to decide who runs Chechnya.
"Is the structure there different in any way from other regions?" he said. "Let's not forget that this is a region of the Russian Federation, where all the laws of the Russian Federation apply."
A Chechen government spokesman did not return calls seeking comment on the expiration of Kadyrov's term.
Kadyrov and his father, Akhmad, were part of a separatist insurgency that fought Moscow's rule in Chechnya in the 1990s. The family switched sides and Akhmad Kadyrov became Chechnya's pro-Moscow leader in 2003 but was assassinated in a 2004 bomb attack. His son, who had been his head of security, was groomed to take over.
Since he was formally appointed by Putin in 2007, Ramzan Kadryov has overseen the rebuilding of the Chechen capital, Grozny, devastated in 1994-96 and 1999-2000 wars by Russian forces intent on keeping Chechnya in Russia.
The reconstruction was bankrolled by Russia and the city now hosts Europe's largest mosque, a multimillion-dollar soccer stadium and a modern skyscrapers complex.
Some in Chechnya see the re-emergence of the city, and the peace that made it possible, as a tribute to Kadyrov, whatever his methods.
But under his rule, Chechnya often seems to operate under its own laws, an anomaly in the rigid system of rule built by Putin in which most regional leaders are Kremlin ciphers.
Chechnya's authorities force women to cover their hair in public spaces and buildings, and they ignore harassment of women deemed to be dressed immodestly, New York-based Human Rights Watch says. Those practices run counter to Russian rules on religious freedom.
According to Russian media reports, on several occasions when Russian federal law enforcement agents have entered Chechnya in pursuit of suspects, their path has been blocked by armed men loyal to Kadyrov.
Kadyrov's style makes some in the Kremlin uncomfortable. He casts himself in the role of a warrior leader whose mission is to uphold Islam and Chechnya's national identity, within Russia.
He attended the wedding of a middle-aged local police chief to a 17-year-old girl last year, a match that was in line with Chechnya's patriarchal moral code but clashed with social norms in other parts of Russia.
His Instagram account mixes images of him at official meetings with shots of him cuddling a lion cub, praying, working out in a gym and attending boxing matches. He sometimes wears suits but more often dresses in a track suit, or camouflage fatigues. Pets he has owned include a lion.
In December last year, a Chechen woman, Ayshat Inayeva, wrote on social media that ordinary people were living in poverty while Kadyrov's circle led extravagant lifestyles. Soon afterward, Kadyrov brought Inayeva and her husband to his office and gave her a dressing down that was broadcast on Chechen television.
Rights activists say there is a darker side to Kadyrov's style. They point to the deaths, disappearance and torture of critics and rivals of Kadyrov, and allege that forces loyal to Kadyrov are responsible. He has denied that.