- Some highly specific information was passed on to the Russian government, despite the frosty relations between Washington and Moscow.
American officials have been quick to confirm that the US has intelligence confirming the Islamic State claim it carried out the attack in Moscow.
The BBC’s US news partner CBS has spoken to a source familiar with the intelligence, who says there has been a steady stream of information - dating back to November - about IS wanting to strike in Russia.
Some highly specific information was passed on to the Russian government, despite the frosty relations between Washington and Moscow.
It has not been confirmed, but it is likely, that this is information that was referred to in the state department warning two weeks ago: Americans in Moscow were told to avoid large gatherings, and specifically warned about concerts.
The State Department said the US was "monitoring reports that extremists have imminent plans to target large gatherings”. The warning did not at that time name the group it was referring to.
The White House has confirmed that it warned Russian authorities earlier in March about an attack possibly targeting "large gatherings" in Moscow.
"Earlier this month, the US government had information about a planned terrorist attack in Moscow - potentially targeting large gatherings, to include concerts," National Security Council spokeswoman Adrienne Watson said.
Washington "shared this information with Russian authorities", she added.
Gordon Corera, the BBC's security correspondent, earlier stated that the Kremlin shrugged these warnings off as "propaganda" - even after the US made its concerns public to Americans staying in Russia.