The Boston bombings show that the West was wrong in supporting militants in Chechnya, Russian President Vladimir Putin says.
He said that "this tragedy should push us (Moscow and the West) closer in fending off common threats, including terrorism, which is one of the biggest and most dangerous of them".
The two brothers accused of the Boston bombings are ethnic Chechens who had lived in the US for more than a decade.
Mr Putin warned against trying to find the roots for the Boston tragedy in the suffering endured by the Chechen people, particularly in mass deportations of Chechens to Siberia and Central Asia on Soviet dictator Josef Stalin's orders.
"The cause isn't in their ethnicity or religion, it's in their extremist sentiments," he said.
Speaking in an annual call-in show on state television, Mr Putin criticised the West for refusing to declare Chechen militants terrorists and for offering them political and financial assistance in the past.
"I always felt indignation when our Western partners and Western media were referring to terrorists who conducted brutal and bloody crimes on the territory of Russia as rebels," Mr Putin said.
The US has urged the Kremlin to seek a political settlement in Chechnya and criticised rights abuses by Russian troops during the two separatist wars since 1994, which spawned an Islamic insurgency that has engulfed the entire region.
It also provided humanitarian aid to the region during the high points of fighting there in the 1990s and the early 2000s.
Russian officials have repeatedly claimed that rebels in Chechnya have close links with al-Qaida.
They say dozens of fighters from Arab countries trickled into the region during the fighting there, while some Chechen militants have gone to fight in Afghanistan.
Mr Putin said the West should have co-operated more actively with Russia in combating terror.
"We always have said that we shouldn't limit ourselves to declarations about terrorism being a common threat and engage in closer cooperation," he said.
"Now these two criminals have proven the correctness of our thesis."