If it is established that Chechens had planted the bombs in Boston, it would mark an unprecedented development: the first time militants from the former Soviet republic have carried out a deadly attack outside Russia.

In their long, violent struggle against the Kremlin, Chechen radicals have hit soft targets before. In 2010, two female suicide bombers from Dagestan blew up the Moscow metro, killing at least 40 people and injuring 100. A year later, another suicide bomber struck Moscow's Domodedovo airport, killing 37 and wounding 180. Other murderous attacks include one on a Beslan school in 2004, where 334 hostages died, most of them children.

But the Boston Marathon bombing, which police suspect was perpetrated by two Chechen brothers, Dzokhar and Tamerlan Tsarnaev, are something altogether new. It is so far unclear how significant is the trail that appears to lead from the simmering ongoing insurgency in the mountains of the North Caucasus to the boulevards and suburban houses of North America.

After 18 years, two wars and the loss of hundreds of thousands of civilian lives, the conflict in Chechnya, and Russia's southern backyard more generally, has changed. From 1994 to 1996, Boris Yeltsin fought a war against mainly secular Chechen separatists who wanted, like other ethnic republics after the USSR collapsed, their own nationalist and constitutional state. From 1999 to 2004, Vladimir Putin – Yeltsin's steely successor – fought a second Chechen war. The aim was to definitively crush Chechen separatism.

In recent years, however, the Kremlin and its regional proxies have been battling a different kind of enemy. This new generation of insurgents has an explicitly Islamist goal: seeking to create a radical pan-Caucasian emirate ruled by Islamic law, like Afghanistan under the Taliban. The movement's leader, Doku Umarov, unveiled this ambitious vision in 2007. He vowed to "liberate" not only Russia's Muslim north Caucasus but a large chunk of European Russia.

Umarov also suggested that devout Muslims should think internationally.

His comments, later softened, said: "Today in Afghanistan, Iraq, Somalia, and Palestine our brothers are fighting. Everyone who attacks Muslims wherever they are, are our enemies, common enemies. Our enemy is not Russia only, but everyone who wages war against Islam and Muslims."

This call to global jihad may perhaps offer a motive for an attack inside the US. As perhaps were trips back to Caucasus by the two bombing suspects. The new generation of twentysomething rebels is also exploiting a powerful new weapon: the internet. The main Chechen rebel website, kavkazcenter.com, posts reports from the jihadist movement worldwide: from Syria, where Chechen diaspora fighters are battling government forces in Aleppo, from Pakistan, and from Turkey.

In the North Caucausus, meanwhile, the Kremlin is carrying out a brutal and rolling counter-insurgency campaign. Its focus is Dagestan, the neighbouring state to Chechnya, and now a hotbed of violent jihadist rebellion. Three weeks ago, Umarov appealed to Chechen fighters abroad to come home to take part in the fight.

Cerwyn Moore, an expert on the insurgency in southern Russian insurgency at Birmingham University, said he was surprised it may have spilled over into the US. "It's a marked change. It seems very odd. There have never been attacks like this outside Russia." But he added: "You have a group of people who have lived outside Chechnya because of the second Chechen war. This is also an inter-generational thing."

Odd or not, the Boston bombings play perfectly into the Kremlin's hands, ahead of Russia's 2014 Winter Olympics, to be hosted in Sochi, not far from where the current insurgency is raging. It reinforces Putin's claim – first made in 1999 – that his violent methods are justified to quell a ruthless rebellion by terrorists prepared to take innocent lives.

Ramzan Kadyrov, the thuggish pro‑Moscow president of Chechnya, sought to distance his republic from the suspects. Taking to Instagram, he said the Tsarnaevs had grown up in the US, adding: "The roots of evil must be searched for in America."