Dagestan, in southern Russia, has a history of violence. Why does it keep happening?

Over the years, Russia's southern republic of Dagestan, located in the North Caucasus region, has been beset by extremist violence. This weekend, there was more bloodshed.

Officials say five gunmen in the regional capital of Makhachkala and the city of Derbent opened fire at Orthodox churches and two synagogues, as well as a police post, killing at least 20 people before being slain by authorities.

The large-scale and coordinated assault raises difficult questions for the Russian authorities about continued security lapses, especially after an attack claimed by an affiliate of the Islamic State group at a Moscow-area concert hall in March killed 145 people.

A look at the volatile region:

Where is Dagestan?

Dagestan, which sits in the North Caucasus between Chechnya and the Caspian Sea, is known as one of Russia's most diverse — but volatile — regions.

There are more than 30 recognized ethnic groups and 13 local languages granted special status alongside Russian.

About 95% of the population identifies as Muslim, according to Russian government statistics, but the region also has long-standing Christian and Jewish communities. The Jewish community dates to the 5th century.

A history of violence

It has been blighted by violence since the early 2000s, when militant insurgents taking part in separatist wars in neighboring Chechnya were pushed into the region as a result of pressure from Russian security forces and iron-fisted Chechen leader Ramzan Kadyrov.

Bombings, attacks on police and kidnappings — all blamed on extremists — were commonplace in the region more than a decade ago,

The bloodshed eased as tougher security measures were imposed before the 2014 Winter Olympics in Sochi, and thousands of militants were believed to have left for Syria and Iraq to fight alongside Islamic State extremists there.

But the region remains restive.

Activists in Russia say ethnic minorities are serving in Ukraine in disproportionate numbers, and videos circulated in October 2022 of protests in Dagestan over complaints that its population was providing more recruits than elsewhere.

In a sign that extremist sentiments still run high, mobs rioted at Makhachkala's airport in October, targeting a flight from Israel. Hundreds of men, some carrying banners with antisemitic slogans, rushed onto the tarmac, chasing passengers and throwing stones at police. More than 20 people were hurt — none of them Israelis.

What happened this weekend?

The attacks took place Sunday night in the city of Derbent and the regional capital of Makhachkala. A group of armed men attacked a synagogue and an Orthodox church in Derbent, the Interior Ministry said.

At the church, attackers slit the throat of the Rev. Nikolai Kotelnikov, a 66-year-old Russian Orthodox priest, before setting the church ablaze, according to Shamil Khadulayev, deputy head of a local public oversight body. The attack came on the day the Orthodox faithful celebrated Pentecost, also known as Trinity Sunday.

Almost simultaneously, reports appeared about an attack on a church, synagogue and a traffic police post in Makhachkala, some 120 kilometers (about 75 miles) to the north.

Russia's Anti-Terrorist Committee said at least five gunmen were killed.

Why is this happening now?

Chambers says several factors contribute to the unrest in Dagestan, including sympathizers to the Ukrainian cause and Russia's ''continuous, tightening repression — particularly in the wake of the large-scale anti-mobilization protests in September of 2022,''

So far, no group has claimed responsibility for the attacks.

Telegram channels associated with the Islamic State affiliate group that carried out the Moscow concert hall massacre praised Sunday's attack by ''our brothers from the Caucasus,'' but did not mention its own involvement.

Dagestan Gov. Sergei Melikov blamed Islamic ''sleeper cells'' directed from abroad, but didn't give any other details. He said in a video statement that the assailants aimed at ''sowing panic and fear,'' and attempted to link the attack to Moscow's military action in Ukraine — but also provided no evidence.

President Vladimir Putin had sought to blame the Crocus City Hall attack in March attack on Ukraine, again without evidence and despite the claim of responsibility by the Islamic State affiliate. Kyiv has vehemently denied any involvement.

How did authorities respond?

''If you're looking at it from a security perspective, you should have concerns because you have a high number of security service casualties,'' Youngman said, noting Russian authorities reported at least 15 security service personnel among the dead.

''I think you would look at the official response and say there are concerns about the security services' ability to protect themselves, let alone others,'' he said.

The Russian state news agency Tass cited law enforcement sources as saying that one Dagestani official was detained over his sons' alleged involvement in the assault.

Concerns remain that Russia's broad security apparatus has not learned the lessons from the Moscow Crocus City Hall concert attack.

Authorities ''were caught off guard'' by Sunday's attack, Chambers said.

There has been no evidence that Russia's ''counterterrorism strategy more broadly will change in the wake of the Crocus City Hall attack,'' Chambers said.