SEARCH FOR SOLUTIONS Strongman Ramzan Kadyrov was installed by Putin to squelch Chechnya's Islamist insurrection. But Kadyrov's adoption of sharia and political Islam in the region are challenging Russia's secular constitutional order. MOSCOW—Russia fought two bloody wars in its Caucasus republic of Chechnya, ostensibly to crush an emerging threat of Islamist extremism on its own soil. So it is with no small irony that the strongman Moscow installed to run a pacified Chechnya, Ramzan Kadyrov, is increasingly posing a similar challenge to Russia's secular constitutional order. Mr. Kadyrov is imposing sharia (Islamic law) on his population – and lately,...