The United States government warned Russia that the Crocus City Hall concert venue in suburban Moscow was a potential terrorist attack target over two weeks before gunmen opened fire on March 22, the Washington Post reported on April 2.
The mass shooting killed at least 143 people in the deadliest terrorist attack Russia has seen since 2004. A branch of the Islamic State known as ISIS-K claimed responsibility for the attack, and U.S. intelligence officials later confirmed the claim.
Citing unnamed U.S. officials, the Washington Post said that the U.S. specifically identified Crocus City Hall as a possible ISIS target in their briefings to Moscow. The disclosure calls into question the Kremlin's claims that U.S. warnings were too "general" to prevent an attack.
Russian President Vladimir Putin publicly dismissed Western warnings of potential terrorist attacks as "outright blackmail" and attempts "to destabilize our society" days before the mass shooting.
Putin has also continued attempting to link the attack to Ukraine, despite ISIS' statements and the lack of evidence pointing to Ukrainian involvement.
Read also: Opinion: Why ISIS attacked Russia and why Russia blames Ukraine
The U.S. regularly shares intelligence about potential terrorist attacks with other countries under the "duty to warn" doctrine, but experts told the Washington Post that disclosing the details of specific targets to an adversary nation is unusual.
The exception may have to do with the risk posed to Americans in Moscow. The U.S. Embassy in Russiaissued a warning on March 7 that "extremists have imminent plans to target large gatherings in Moscow" and urged American citizens to stay away from crowded areas and venues over the next 48 hours. The U.K., Canada, Germany, and several other countries published similar statements soon after.
The warning about Crocus City Hall did not lead to increased security measures at the venue. Video footage of the attacks shows the assailants facing little resistance, and specialized police units did not arrive at the scene until the gunmen had already fled.
Iran also reportedly warned Russia of the threat of a major "terrorist operation" on Russian soil ahead of the Crocus City Hall shooting.
Ukraine's military intelligence chief Kyrylo Budanov said on March 27 that Putin was made aware of the terror threat by Feb. 15 at the latest.
Read also: Moscow shooting aftermath: Repressions, racism, terror