“who says they didn’t know???”
That’s what I keep asking. There were so many indicators out there, the US Govt had to know that these guys were up to no good. So why didn’t the US do anything?
What I believe the Russians suggested is that the US authorities were running them as US agents. They got away with all that because the US thought they were OUR terrorists. When they bombed the marathon, the CIA or whoever was running them must have really needed to change their underwear!
But that explains why they were left alone and no leads from the Russians were ever followed.