Ah yes, "U.S. Counter terrorism Officials and Analysts said."
Has to be true then.
"The United States collected intelligence in March that
Islamic State-Khorasan, known as ISIS-K, the branch of the group
based in Afghanistan, had been planning an attack on Moscow, according to officials. ISIS members have been active in Russia, one U.S. official said."
Apparently the U.S. is Duty bound to inform both Iran and Russia when they get info of an impending attack,because we all know the last thing the Officials and analysts want are innocent civilians dead.
As with most things surrounding attacks and conflicts nowadays,we are going to get a deluge of "info" immediately from the main players in Western media who are spoon fed,and then as time goes there will be an aggregation of the facts.