Story highlights On Monday, at least 14 people were killed in an explosion on the St. Petersburg metro

Peter Bergen and David Sterman: The attack is most likely the work of ISIS perpetrators

Peter Bergen is CNN's national security analyst, a vice president at New America and a professor of practice at Arizona State University. He is the author of "United States of Jihad: Investigating America's Homegrown Terrorists." David Sterman is a policy analyst at New America's International Security Program.

(CNN) According to Russia authorities, Monday's suicide bombing on the St. Petersburg metro was carried out by Akbarjon Djalilov, 22, from Kyrgyzstan, a Central Asian republic of the former Soviet Union.

The fact that a second bomb was found at another St Petersburg metro station indicates that Djalilov was likely not acting alone and was part of larger conspiracy.

Peter Bergen

David Sterman

There are two groups that have both the capability and the intent to carry out large-scale terrorist attacks in Russian cities. First, there are Chechen separatists who have mounted a wide range of terrorist attacks in Russia. The Russians have been waging wars with these separatists since the 19th century, but for obvious reasons Chechen separatist terrorism tends to be carried out by Chechens.

The other, more likely perpetrator, ISIS has plotted to target St. Petersburg in the recent past.

In February 2016, Russia arrested seven alleged ISIS militants who were plotting attacks in St. Petersburg and Moscow. The group included Russians and Central Asians and a ringleader who had come from Turkey. Russian authorities said they had discovered firearms and a bomb-making laboratory.

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