Hours after the Boston bombers were identified as Chechens, President Vladimir Putin of Russia called President Barack Obama to offer help with his investigation.

Putin long has argued that Russia faces the same threat of radical Islam in the northern Caucasus as the West does elsewhere. The Boston bombings seem to support him.

He is right in one respect. The war in Russia's southern underbelly no longer is a separatist conflict. The nationalist cause that inspired Chechen fighters 20 years ago is now an Islamic one. However, this mutation has as much do with Russia's ruthless actions in the region as with the global spread of Islamist fundamentalism.

So far America, Russia and even the insurgents agree that Dzhokhar and Tamerlan Tsarnaev, the Boston bombers, acted on their own. The self-proclaimed Caucasus Emirate, a jihadist organization, says that it played no part.

Nonetheless, America's investigators find it hard to understand how a regional conflict in Russia might resonate tragically in Boston.

Struggling to integrate in America — "I don't have a single American friend," Tamerlan, the older brother, once said — the Tsarnaev boys sought mental refuge in their native land. The Internet and social networks that served as a channel created an illusion of engagement without experience or memory. The brothers never fought in the Chechen wars or lived in Chechnya for any length of time, yet their lives and their sensibilities seem to have collided with its violent and tragic history.

After the mass deportation of Chechens by Stalin in 1944, the Tsarnaev family landed in Kyrgyzstan, where the boys later grew up. Their grievances were stirred by separatists who declared Chechnya's independence after the end of the Soviet Union in 1991. When Russia launched a "small, victorious war" against Chechnya in 1994, nationalism was the main cause. By the end of the first war, 50,000 were dead, Chechnya was in ruins — and nationalism had been superseded by Islam.

The second war began in 1999 with an incursion of Chechen rebels into Dagestan, with the aim of freeing their Muslim brothers from occupation by infidels. The Islamization of the conflict opened up a fierce sectarian fight between Sufism, a traditional form of Islam based on local customs, and Salafism, a more radical form that promotes sharia law.

In Chechnya, Sufi leaders sided with the Russian state to eradicate Salafism. After the 2003 assassination of President Akhmad Kadyrov, his son and successor, Ramzan Kadyrov, redoubled these efforts, hunting down Salafists and enforcing Sufism as a state ideology. Chechnya now boasts Europe's largest mosque, women are covered and polygamy is encouraged. Even as Kadyrov has "pacified" it, however, violence has spread, including to Dagestan, where the Tsarnaev brothers lived before going to America.

By the late 2000s, the Salafis in Dagestan were winning support among young Muslims, many of whom studied in the Middle East, whereas Sufis were tainted by association with a corrupt and dysfunctional state. The government responded by trying to soften its tactics. Persecution eased, Salafi mosques were allowed to open and a commission for the rehabilitation of fighters was set up.

The rise of moderate Salafism indeed has cut the number of young people becoming terrorists. The numbers killed and injured in Dagestan dropped by 15 percent in 2012, according to Grigory Shvedov, head of the Caucasian Knot, a human-rights monitoring organization.

"People felt there was an alternative to the armed struggle," says Ekaterina Sokirianskaia, who covers the north Caucasus for the International Crisis Group.

Nonetheless, new Salafism posed a threat both to armed radicals and to corrupt officials. Moscow too frets about the emergence of Salafi institutions, which could become an alternative to the Russian state. So, with Vladimir Putin back in the presidency, Russia has reverted to hard power. The soft-approach president of Dagestan has been replaced by a much tougher man. The rehabilitation commission has been shut down. A recent counterinsurgency operation in one mountainous region of Gimry led to the displacement of its entire population.

Shvedov says that this kind of "mopping up" is part of Russia's preparation for the 2014 Winter Olympics in nearby Sochi.

The Boston bombs may create sympathy in America for Russia's tough policy in the north Caucasus. In the long run, though, suppression alone is unlikely to bring greater security to Russia.

From the Economist magazine.