''But the US has a vast intelligence-gathering machine and watches IS closely. The branch suspected of the Moscow attack was also linked to one on US forces and civilians at Kabul airport in August 2021, as well as more recent deadly bombings in Iraq.
But if the intelligence that was shared with Russia was credible and specific about IS, then the FSB and Mr Putin might appear to be on the back foot about why they did not take it more seriously.
And if so, it may be easier for Moscow to relate the attack in some way to Ukraine in order to deflect blame and also build support for Russia's actions there, rather than acknowledge what they might have missed."
