Chechnya — the war-torn hotbed of terrorism on Russia's southern periphery — has been relatively quiet since Islamic militants from the region threatened but failed to disrupt the Winter Olympics in Sochi earlier this year.

That changed Sunday when a suicide bomber blew himself up in the Chechen capital of Grozny, killing five people and injuring 12 others, according to the Russian government-controlled RIA Novosti news agency.

The bomber —19-year-old Opti Mudarov — detonated a bomb as police stopped him before he entered a hall to attend a concert commemorating City Day, a local holiday.

The timing of the explosion was obviously symbolic. City Day is held on the birthday of Chechen President Ramzan Kadyrov, a former insurgent who changed sides and became a close ally of Russian President Vladimir Putin.

Kadyrov runs the semi-autonomous Chechen Republic with an iron fist with the help of Putin, who has spent billions of dollars rebuilding Grozny after Russian forces leveled the city to suppress two rebellions against Moscow that erupted there in the 1990s.

Human rights groups have accused Kadyrov and his supporters of torturing enemies, killing journalists, and running death squads. He once opined that honor killings are okay because wives are the property of their husbands.

In characteristic fashion, Kadyrov said he would root out and punish those who planned the attack.

"These devils have shown their true colors. We'll show them that they do not belong to this soil," he said to RIA Novosti. "All those involved in this bombing will be found and destroyed."

'All those involved in this bombing will be found and destroyed.'

It's not clear if the bombing has any connections to Russia's aggression in Ukraine and Crimea, where Muslim Tatars oppose Moscow's rule, or the Islamic State's rise in Iraq and Syria, said Jeffrey Mankoff, a Russian expert at the Center for Strategic and International Studies. But the explosion was counter to recent trends of violence waning in Grozny but waxing in nearby Dagestan and Ingushetia.

Seven years ago, despite Russia's brutal crackdown on separatists, Chechen terror mastermind Doku Umarov declared a Caucasus Emirate in the region. Last year, saying the Olympics would take place on the "bones of our ancestors," he called for attacks against the games. Russian officials claimed they killed him a few months later.

While Umarov's followers successfully attacked trains and buses in Volgograd — a city around 600 miles away from Sochi — and a female Chechen "black widow" terrorist was suspected of infiltrating the Olympic compound, the games went off without a hitch.

Now it seems Chechen terrorists are back.

"The fact that it occurred in Grozny is significant," Mankoff said. "Going back to the Olympics and before, the bulk of the attacks had been occurring outside Chechnya. Kadyrov has clamped down on things happening in his fiefdom even as the situation on the ground in the rest of the North Caucasus was getting worse and worse."

Also concerning was how the bomber, Mudarov, reportedly had disappeared for two months. Nobody knows where he went, but Mankoff knew one place where he might have been radicalized.

"There are a fairly significant number of Chechens fighting in Syria," Mankoff said. "Kadyrov and Putin and others have expressed concern. Obviously at some point they [the Chechen Islamic State fighters] are going to come back, and there is going to be some kind of blowback. Whether that is an example of blowback, we don't' know."