U.S. officials say Russian authorities secretly recorded a conversation in 2011 in which one of the Boston bombing suspects vaguely discussed jihad with his mother.
Officials say a second call was recorded between the suspects' mother and a man under FBI investigation living in southern Russia.
The officials spoke on condition of anonymity because they were not authorized to speak publicly about the ongoing case.
They say the Russians shared this intelligence with the U.S. in the past few days.
The conversations are significant because, had they been revealed earlier, there might have been enough evidence for the FBI to initiate a more thorough investigation of the Boston bombing suspects' family.