If the U.S. warning was so detailed, it raises further questions about Russia’s failure to prevent the country’s worst terrorist attack in two decades. But rather than publicly confronting questions about their own actions, Russian security officials have disregarded the claims of responsibility by the Islamic State.

Instead, they have insisted that U.S. and British intelligence were involved in helping Ukraine organize the strike.

Kremlin spokesman Dmitry Peskov declined to comment Wednesday on a report in The Washington Post that U.S. intelligence specifically warned Russia that Crocus City Hall could be a target for terrorists. The New York Times published a similar report shortly after The Post.

Russian Security Council Secretary Nikolai Patrushev on Wednesday directly blamed Ukrainian security services for the Crocus City Hall attack, in which at least 114 people were killed. Patrushev also hinted at Western involvement.

A day earlier, he accused Western intelligence of using terrorist groups to attack adversaries.

“They are trying to make us think that the terrorist attack was perpetrated not by the Kyiv regime but by followers of radical Islamic ideology, possibly members of the Afghan branch of [the Islamic State],” Patrushev said at a meeting in Astana, Kazakhstan, of security council secretaries of the Shanghai Cooperation Organization nations. He said it was more important to identify the “masterminds and sponsors,” squarely blaming Ukrainian security services. He added that numerous hoax bomb threats have emanated from Ukrainian territory since the attack.

“It is also indicative that the West began insisting on Ukraine’s noninvolvement in the crime as soon as the terrorist attack on Crocus City Hall was reported,” Patrushev said.

Russia’s blame game comes amid increasingly confrontational anti-NATO rhetoric from top security officials who insist that the U.S.-led alliance is fighting a “war” against Russia. Several of these officials have hinted repeatedly about Russia’s potential use of nuclear weapons.

NATO officials continue to assert the alliance’s right to supply Ukraine the weapons it needs to defend its territory.

Since the Crocus City Hall attack, Russian officials have subtly framed the violence as part of that “war,” while barely mentioning the Islamic State’s Afghanistan branch, Islamic State-Khorasan, or ISIS-K, which U.S. intelligence officials have said was responsible.

U.S. intelligence also warned last month that terrorists could attack a Moscow synagogue. A day after receiving the warning, on March 7, Russia’s Federal Security Service (FSB) announced that it had prevented an attack on a Moscow synagogue by an ISIS-K cell.

Asked if the United States warned Russia that Crocus City Hall was a possible target for a terrorist attack and whether a U.S. warning helped the FSB avert the synagogue attack, Peskov on Wednesday declined to confirm the report.

“Okay, I see,” he said. “This is not our competence because such information exchanges are conducted at the level of specialized services, and the information is transmitted directly from service to service.”

The spokeswoman for Russia’s Foreign Ministry, Maria Zakharova, on Wednesday alleged a disinformation campaign by Washington and said the U.S. government should prove that the reports in The Post and the Times were true by disclosing when and to whom the detailed warning was given.

At least two members of the cell that planned the synagogue attack, based in the Kaluga region, were killed by FSB agents when they opened fire during arrest, according to the agency, which reported that the cell was planning to attack the synagogue using firearms. Kazakhstan confirmed that two of its citizens were killed in the raid.

Four days after the Crocus City Hall attack, FSB Director Alexander Bortnikov blamed Ukraine and said Western security services were involved.

“We believe that the action was prepared by radical Islamists, naturally, Western security services contributed to it, and Ukrainian security services bore a direct relation,” Bortnikov told reporters.

Patrushev told Argumenty i Fakty newspaper in an interview published Tuesday that Washington used NATO as a tool to carry out hybrid wars “to undermine and disorganize the system of state administration of countries that do not agree with the policy of the Anglo-Saxons.”

“At the same time, the alliance does not disdain using terrorist organizations in its interests,” he said. NATO, he said, “has been a source of danger, crises and conflicts for many years.”

Three days before the Crocus City Hall attack, Russian President Vladimir Putin had dismissed the U.S. warnings, calling them “outright blackmail” and attempts to “intimidate and destabilize our society.”

Putin and other Russian officials have made no mention of the U.S. intelligence supplied in relation to the planned synagogue attack.

In an interview with Argumenty i Fakty published on the morning of the Crocus City Hall strike, Peskov said NATO was waging a war against Russia, repeating a linchpin of Kremlin propaganda used to justify Russia’s invasion of Ukraine and to mobilize Russia’s population behind the war.

“We are in a state of war. Yes, it started out as a special military operation, but as soon as that bunch formed there, when the collective West became a participant in this on the side of Ukraine, it has already become a war for us. I am convinced of that. And everyone should understand this, for their internal mobilization,” Peskov said.

Putin alleged a Ukrainian link to the Crocus City Hall terrorists the day after the attack when he told Russians in a speech to the nation that “a window was prepared for them from the Ukraine side to cross the state border.”

Top pro-Kremlin propagandists, including Margarita Simonyan, editor in chief of the RT news channel, ramped up attacks blaming Ukraine and the West. In a post on social media, she asserted that Western intelligence clearly played a direct role in the Crocus City Hall attack because it had identified the perpetrators.

“They knew who the perpetrators were. Before the detention. That’s direct involvement,” Simonyan posted, later adding that the source of the attack was “not ISIS,” but Ukraine.

Likewise, Russian lawmaker Alexander Yakubovsky claimed that “the Nazi terrorist regime of Ukraine is behind this terrorist attack, possibly using radical Islamists, but without Western intelligence services it is impossible to pull this off.”

Another hard-line Russian lawmaker, Pyotr Tolstoy, posted on Telegram that the war could not be seen apart from “the war with the collective West for the peaceful futures of our children.”

The Kremlin’s effort to blame Ukraine and the West for the attack appears to have succeeded in mobilizing Russians around the war effort. Russia’s Defense Ministry announced Wednesday that 1,700 Russians a day were signing contracts to fight in Ukraine, many of them, it added, motivated by the Crocus City Hall attack. In the past 10 days, 16,000 people have signed contracts, it announced.

Shortly after the U.S. warnings were shared with Russia, the authorities did tighten security at Crocus City Hall, according to a 15-year-old coat-check boy, Islam Khalilov. He told Russian media: “We were warned a week ago that there might be attacks. There was training. They told us what to do, where to lead people. I was ready for it in principle. That week there were the toughest checks, with dogs.”

But just days later, on a busy Friday evening, four gunmen rampaged through Crocus City Hall, shooting concertgoers and setting the hall on fire without any resistance, according to video from the scene.

It remains unclear why security was loosened again. Russian officials — and pro-Kremlin news outlets — have steered clear of the question, instead focusing on blaming Ukraine and the West.

Putin, speaking at an Interior Ministry meeting Tuesday, called for increased security at concert venues, shopping centers and other places where crowds gather.

“It’s important above all to bring law, order and security at crowded places, at sports and transport facilities, shopping and recreation centers, schools, hospitals, colleges, theaters and so on up to a new level,” he said.

Russia’s foreign intelligence chief, Sergei Naryshkin, claimed Tuesday that U.S. intelligence on the Crocus City Hall attack was too general to be of help.

“Indeed, the FSB did receive information,” he said. “The information was too general and did not allow the ultimate identification of perpetrators of the horrible crime.”

Shane Harris in Washington and Natalia Abbakumova in Riga contributed to this report.