The US cannot recognize valuable intel from Russia because it's accuracy puts the lie to the US war on Serbia and Christian Slavs, and criminalizes the US government, agencies, and government employees.
The info on terrorist attack from FSB was against all that US policy in last 20 years. By accepting warning, US gov. would admit that all it has been done in pas 20 years was WRONG.
Therefore the info was rejected.
Simple math- It is much less damage to led bombs go off and lose some American lives than to admit that gov. was wrong.
Like Chernobyl in USSR. It blew up and commie gov. kept it quiet letting people be exposed to radioactive rain on Mayday parade...
Commie is what commie does.