Two female suicide bombers killed at least 38 people on packed Moscow metro trains during rush hour on Monday, stirring fears of a broader campaign in Russia's heartland by Islamists from the North Caucasus.
Here is some reaction:
CHRIS WEAFER, CHIEF STRATEGIST URALSIB INVESTMENT BANK, MOSCOW (Mr. Weafer was commuting to work on the train behind the one in which a bomb exploded at Park Kultury station. His train halted one station away from the scene of the blast.)
If it proves to be a one-off event then the impact is minimal, we can see that today where markets are up because of other factors. The view of markets is these are one-off events and will have a negligible impact.
But, if it proves that this is the start of a series of attacks, then the markets would take a different perspective.
GRIGORY SHVEDOV, CHIEF EDITOR OF CAUCASIAN KNOT INTERNET NEWS AGENCY, WWW.CAUCASIANKNOT.INFO
It was obvious after the Nevsky Express train bombing in November that this would happen more and more.
Society needs to understand and act differently about what is going in the North Caucasus. I am waiting for confirmation, but it seems very likely that it was carried out by groups from the North Caucasus.
I fear very much explosions on trains. Buses are also a target, anywhere large groups of people gather, especially in central Moscow.
NIGEL INKSTER, INTERNATIONAL INSTITUTE FOR STRATEGIC STUDIES
The Moscow bombing is a predictable response to a policy towards the North Caucasus which combines reliance on local proxies who are corrupt and incompetent with a security policy focused almost entirely on retaliation, repression and the resort to extra-judicial techniques such as targeted killings, reprisals against the families of terrorists and torture.
Over the past three years, the level of terrorist incidents in the North Caucasus has risen inexorably -- 460 last year according to Jane's -- and the level of seriousness has also increased. And what started out as mainly ethno-separatist rebellions in individual states have become increasingly susceptible to incorporation into a wider Islamist movement, the North Caucasus emirate under Chechen leader Doku Umarov.
I doubt this will affect [Prime Minister Vladimir]Putin too much. All we are likely to see is a reaffirmation of existing policies which will be popular with the Russian man in the street.
MATTHEW CLEMENTS, EURASIA ANALYST, IHS JANE'S INFORMATION GROUP
This could see a strengthening of the hand of the hardliners in the Kremlin towards a tougher approach to the insurgency.
This could involve a stepping away from the dual approach of pursuing social and economic development alongside security action. There had been a realization that you need to attack the root causes of the violence with a comprehensive strategy on poverty and localized corruption.
The escalation of insurgency in the region means the central government's approach is not succeeding in reducing violence. The groups are becoming more active, more organized and more co-ordinated, where once they were disconnected local groups.
GALINA YEMELIANOVA, SENIOR LECTURER, CENTRE FOR RUSSIAN AND EAST EUROPEAN STUDIES, UNIVERSITY OF BIRMINGHAM
The use of suicide is against Caucasian tradition so this kind of attack is another indication of the incorporation of jihadist tactics into the North Caususus insurgent groups.
The groups receive a continuous flow of young people prepared to blow themselves up. The networks also continue to recruit women. Often they have lost everything -- husbands, brothers, children -- and they are willing to kill themselves as revenge.
The method of suppression by the federal government in the north Causasus has been quite counter-productive. It has pushed the insurgency out of Chechnya. It is increasingly multi-ethnic and is spreading to other parts of the region through underground jihadist networks which have become more and more active.
HENRY WILKINSON, JANUSIAN SECURITY CONSULTANTS
It is highly likely that this was the work of Caucusus Emirate network -- possibly its Riyad-us-Saliheen Martyr Brigade -- which is fighting to establish an Islamist state in the North Caucusus. There has been a clear year-on-year increase in attacks in the North Caucusus -- particularly in Ingushetia, Dagestan, and Chechnya -- where we see several attacks a day.
With this and the deaths of several senior terrorists in recent months, the threat of revenge attacks and atrocities spilling out of the region has been acute. Its re-emergence in Moscow in the form of major co-ordinated suicide bombings like these seemed more a matter of when rather than if, and will be very embarrassing for the Russian government.
JUSTIN CRUMP, STIRLING ASSYNT BUSINESS INTELLIGENCE
Jihadists had threatened to escalate their campaign in the Russian heartland and infrastructure targets are one of their stated objectives. They said in recent messages that "the battle" would reach Moscow and it looks like they've made good on this threat and an earlier one to extend attacks into Western Russian.
JONATHAN EYAL, ROYAL UNITED SERVICES INSTITUTE
This is a direct affront to Vladimir Putin, whose entire rise to power was built on his pledge to crush the enemies of Russia. It is an affront to his muscular image. The real problem at this point is political. Putin is not in Moscow today but when he returns the question is whether he emerges from this strengthened or not.
On the security side it looks very similar to a previous strike on the underground in Moscow and the involvement of women recalls the Black Widows [believed to be women who have lost brothers or husbands in the Chechen conflict] The fact of the matter is that there is very little you can do to protect against this kind of attack without shutting down the entire transport system.
RAPHAEL PERL, ORGANISATION FOR SECURITY AND COOPERATION IN EUROPE
If the attacks were confirmed as suicide bombings then my gut reaction would be that this was related to the North Caucasus but you cannot definitively say that [without specific information] No one has a monopoly on this kind of attack.
BEN VENZKE, INTELCENTER, U.S.-BASED TERRORISM MONITORING COMPANY
The most likely group behind the twin suicide bombings in the Moscow subway today is the Caucasus Emirate lead by Doku Umarov. On both 28 Dec. and 14 Feb, Umarov had threatened to conduct attacks targeting Russian civilians at their homes. The group has both the demonstrated capability to conduct this type of attack and expressed intent.