DW: Who in Russia is in a position to organize terrorist acts like we've seen in Volgograd?

Yekaterina Sokiryanskaya: There are numerous terror groups in Russia, but in the case of Volgograd, I'm completely certain that it's the Caucasus Emirate. Its leader Doku Umarov published a video address at the end of July in which he threatened to sabotage the Olympic Games in Sochi. The suspected suicide bomber was of Russian ethnicity, but he belonged to the Caucasus Emirate. Although Doku Umarov did not claim responsibility for the first terror strike in October, nor for the last two, I'm absolutely certain that these attacks are the realization of his threats.

What's known about this group?

The Caucasus Emirate came into being in 2007 in conjunction with changes in the separatist movement in Chechnya. The UN, Russia, the US and other countries have classed the group as terrorists. At first, it operated in the North Caucasus region. Now there are reports that a cell is also active in Tatarstan. Traditionally, Chechens have been at the head of the Caucasus Emirate, but since 2009, the Republic of Dagestan has become the center of its activities.

The group has a complicated structure. In a few administrative districts, or vilayets, it has its own emir, meaning a leader, as well as a kadi - a judge. The vilayets function largely autonomously even though they pursue common goals. There are sympathizers there. Some people reject armed conflict but don't recognize the Russian authorities. For them, the kadis and Sharia law are the highest authorities.

The Caucasus Emirate finances up to 90 percent of its activities itself. It blackmails regional offices and business people. And everyone pays because the police cannot protect them. Many don't even report the blackmail or the "jihad tax" because it involves illegal earnings. The Caucasus Emirate doesn't depend just on an ideology but also on criminal sources of income.

Are there other terrorist groups that are comparably strong?

No. There are other terror groups, but none of them have as much power as the Caucasus Emirate. But one also has to admit that the security forces are very successful. Each year, part of the group's leadership is eliminated - for example, in the Kabardino-Balkar Republic. But the structure is arranged so that it regenerates itself.

When it comes to terrorist threats, I want to mention a new phenomenon in Russia: radicalized lone perpetrators, like the Tsarnaev brothers in the US. They're people waging total jihad who do not belong to any organization. After all, you can build a bomb these days using instructions from the Internet. It doesn't take any bigger operation in terms of money or an organization to carry out a terrorist act. It just takes a suicide murderer to get on a bus.

How many potential terrorists are thought to be residing in Russia?

No one knows for sure. In the entire North Caucasus, estimates range from 1,000 to 1,500 people. But these days, terrorists don't need big armies. They would have to be housed illegally and fed - those would be additional costs. The groups have a lot of interest from recruits, but not everyone is taken on. But even a small number of people can represent a serious threat. If you include those supporting the direct accomplices, then it's around 2,000 to 3,000 people, but no more.

What role does radical Islam play?

There's no doubt that a radical interpretation of Islam is playing a key role, particularly Salafism. These people consider themselves as part of the global jihad. There are also fighters from Russia in Syria - where people estimate there are 1,500 to 2,000 jihadists from the North Caucasus.

However, not all Muslims are radicalized. In Dagestan, there are a great many Salafists, but most reject terrorist methods. An attempt was made in 2011 and 2012 to integrate these people. As of January 1, 2013, though, the republic has a new government that is taking ruthless and drastic action. Salafism is being pushed toward illegality. In the last few months, 30 to 40 people were arrested daily. People are indiscriminately singling out bearded men, women with headscarves. Moderate leaders are moving abroad, while radicals take their places. I was in Dagestan not too long ago and saw how young people are being radicalized by violence perpetrated by local authorities.

It's easy to assume these terror acts are also going to target the Olympic Games in Sochi. There will be immense security measures in place. What's your view on that?

The danger of terrorism is real. And the incredible efforts being undertaken in Sochi and other Russian cities cannot guarantee that nothing will happen during the Games. You see how little it takes to commit an act of terrorism. Nevertheless, I hope that it's possible to maintain security during the games.

Yekaterina Sokiryanskaya heads the International Crisis Group's Russia chapter.