A day earlier than the U.S. embassy in Moscow put out a uncommon public alert this month a couple of potential extremist assault at a Russian live performance venue, the native C.I.A. station delivered a personal warning to Russian officers that included at the very least one extra element: The plot in query concerned an offshoot of the Islamic State generally known as ISIS-Ok.

American intelligence had been monitoring the group intently and believed the risk credible. Inside days, nevertheless, President Vladimir V. Putin was disparaging the warnings, calling them “outright blackmail” and makes an attempt to “intimidate and destabilize our society.”

Three days after he spoke, gunmen stormed Crocus Metropolis Corridor outdoors Moscow final Friday night time and killed at the very least 143 individuals within the deadliest assault in Russia in almost 20 years. ISIS shortly claimed duty for the bloodbath with statements, a photograph and a propaganda video.

What made the safety lapse seemingly much more notable was that within the days earlier than the bloodbath Russia’s personal safety institution had additionally acknowledged the home risk posed by the Islamic State affiliate in Afghanistan, referred to as Islamic State Khorasan Province, or ISIS-Ok.

Inner Russian intelligence reporting that almost certainly circulated on the highest ranges of the federal government warned of the elevated probability of an assault in Russia by ethnic Tajiks radicalized by ISIS-Ok, based on info obtained by the File Middle, a London analysis group, and reviewed by The New York Occasions.

Russia has recognized the 4 males suspected of finishing up the assault as being from Tajikistan.

Now, Mr. Putin and his lieutenants are pointing fingers at Ukraine, making an attempt to deflect consideration from a query that may be entrance and heart in any nation with an unbiased media and open debate in its politics: How did Russia’s huge intelligence and legislation enforcement equipment, regardless of vital warnings, fail to go off one of many largest terrorist assaults within the nation in Mr. Putin’s almost quarter century in energy?

The total image remains to be unclear, and U.S. and European officers, in addition to safety and counterterrorism specialists, emphasize that even in the very best of circumstances, with extremely particular info and well-oiled safety providers, disrupting covert worldwide terror plots is tough.

However they are saying the failure almost certainly resulted from a mix of things, paramount amongst them the deep ranges of mistrust, each inside the Russian safety institution and in its relations with different world intelligence companies.

Additionally they level to the way in which Mr. Putin has hijacked his home safety equipment for an ever-widening political crackdown at house — in addition to his concentrate on crusading towards Ukraine and the West — as distractions that most likely didn’t assist.

This account of the Russian failure to forestall the live performance assault is predicated on interviews with U.S. and European safety officers, safety specialists and analysts specializing in worldwide intelligence capabilities. Many spoke on the situation of anonymity to debate delicate intelligence particulars.

“The issue is to really be capable to forestall terrorist assaults, it’s essential to have a extremely good and environment friendly system of intelligence sharing and intelligence gathering,” mentioned Andrei Soldatov, an professional on Russian intelligence, who underscored that belief is required inside the house company and with companies of different international locations, as is nice coordination. He mentioned, “That’s the place you’ve issues.”

An Increasing Definition of Extremist

Mr. Putin’s definition of what constitutes an extremist started to develop even earlier than his invasion of Ukraine in early 2022.

The company primarily answerable for combating terrorism in Russia known as the Second Service, a department of the Federal Safety Service, or the F.S.B. It as soon as centered on Islamist extremists, bands of assassins and homegrown neo-Nazi teams.

However as Mr. Putin has superior his political crackdown at house, its record of targets ballooned to incorporate opposition figures like Aleksei A. Navalny, who died final month in a Russian jail, and his supporters, in addition to L.G.B.T.Q. rights activists, Jehovah’s Witnesses, peace activists and different Kremlin critics.

The variety of Islamist-related organizations on the register of extremist organizations listed by Russian Federal Service for Monetary Monitoring has declined since 2013. On the identical time, tons of of organizations have been added associated to Jehovah’s Witnesses, which has its worldwide headquarters in america and is seen with suspicion by the F.S.B.

Safety specialists mentioned the increasing focus wasted sources and diverted the eye of senior leaders.

The top of the Second Service, as an illustration, was more and more concerned in areas far afield from counterterrorism; in 2020, based on the U.S. authorities, he and his department of the F.S.B. had been concerned in the poisoning of Mr. Navalny.

“General, the F.S.B. is a political police drive, and as such it displays Kremlin issues,” mentioned Mark Galeotti, a specialist on Russia’s safety operations and a senior affiliate fellow on the Royal United Providers Institute in London. “At current, the federal government is most exercised by political dissent and Ukrainian sabotage, so they’re the F.S.B.’s priorities.”

Russia is among the chief army backers of the Islamic State’s opponents within the Center East, together with Syria’s Bashar al-Assad, making Russian pursuits a key goal of the Islamist extremist group. However as one European safety official put it, the Russians had been pursuing “fictitious threats” relatively than actual ones.

Nonetheless, U.S. and European officers say the Russian officers monitoring Islamist extremists have their very own unit inside the Second Service that has remained robustly staffed and funded, regardless of the strains on the safety providers from the intensifying home political crackdown and the battle towards Ukraine.

The failure to forestall the assault was most likely the results of a mix of different elements, together with fatigue after being “particularly alert” through the interval earlier than Russia’s latest presidential election, mentioned a European safety official, who tracks the actions of the Russian intelligence providers.

There’s additionally proof that Russian authorities did reply to the warnings this month, at the very least initially.

Elevated Safety

On March 7, the day after the C.I.A. station issued the non-public warning to the Russians, the F.S.B. introduced that it had killed two Kazakhs southwest of Moscow, whereas disrupting an ISIS-Ok plot to focus on a synagogue within the capital. U.S. officers thought the raid was probably an indication that the Russian authorities had been springing into motion.

Iosif Prigozhin, a well known Russian music producer, recalled that he and his spouse, the Russian pop star Valeriya, who carried out at Crocus Metropolis Corridor this month, observed how safety had elevated on the venue in early March; safety guards checked individuals’s baggage and cosmetics circumstances and took different measures he hadn’t seen there earlier than, he mentioned.

“I even referred to as the final director and mentioned, ‘Hear, what’s occurring? Are you anticipating high-ranking company?’” Mr. Prigozhin mentioned in an interview. “He mentioned, ‘Iosif, I’ll let you know later.’ He didn’t say something over the cellphone. He mentioned it’s mandatory — and that’s it.”

Across the identical time, the venue’s employees was warned about the potential of a terrorist assault and instructed on what to do in such an occasion, mentioned Islam Khalilov, a 15-year-old pupil who was working within the coat examine on the night time of the assault, in an interview posted on YouTube.

One in all Mr. Putin’s favourite singers, Grigory Leps, was performing there on March 8. Shaman, a singer whose pro-Kremlin jingoism has catapulted him to recognition amid wartime fervor, was scheduled to take the stage a day later.

However the heightened safety didn’t ferret out one of many attackers, Shamsidin Fariduni. Staff on the music corridor, talking to Russian media, recalled seeing Mr. Fariduni on the live performance venue on March 7. A photograph of him in a lightweight brown coat on the venue, verified by The Occasions, has circulated within the Russian press.

Aleksandr V. Bortnikov, the director of the F.S.B., emphasised Tuesday in public feedback that the knowledge america supplied was “of a basic nature.”

“We reacted to this info, in fact, and took applicable measures,” he mentioned, noting that the actions the F.S.B. took to comply with up on the tip didn’t verify it.

The adversarial relationship between Washington and Moscow prevented U.S. officers from sharing any details about the plot past what was mandatory, out of worry Russian authorities may study their intelligence sources or strategies.

In its March 7 public warning, the U.S. embassy mentioned the danger of a live performance venue assault in Moscow was acute for the following 48 hours.U.S. officers say it’s potential Russian authorities pushed arduous across the 48-hour warning interval however later grew extra relaxed and distrustful when an assault didn’t happen.

It’s unclear whether or not U.S. intelligence mistook the timing of the assault or the extremists delayed their plan upon seeing heightened safety.

Within the subsequent days, inner Russian intelligence reporting — which the File Middle mentioned reached the Russian Nationwide Safety Council — warned particularly concerning the risk that Tajiks radicalized by ISIS-Ok posed to Russia. The reporting pointed to the involvement of Tajiks in disrupted plots in Europe and assaults in Iran and Istanbul in latest months. The reporting didn’t point out the Western warnings or a potential Moscow assault.

The File Middle was based in by the exiled Russian tycoon Mikhail B. Khodorkovsky, a longtime opponent of Mr. Putin. The authenticity of its report couldn’t be independently verified.

However by then, the skepticism concerning the plot had grown inside the Russian authorities, and Mr. Putin felt snug deriding the general public warnings in a speech to high officers on the F.S.B., utilizing the event to assault the West once more.

“As a result of the F.S.B. — and Putin — sees the world by means of the prism that america is out to get Russia, any info that isn’t in keeping with that body is definitely dismissed,” mentioned Andrea Kendall-Taylor, a senior fellow on the Middle for a New American Safety, who beforehand led analyses of Russia by the U.S. intelligence neighborhood.

She mentioned, “That dynamic might have resulted in an intelligence failure with devastating penalties.”

‘Responsibility to Warn’

When it knowledgeable Russia privately concerning the potential terror plot, the C.I.A. was adhering to 2015 steering generally known as “obligation to warn” directives, requiring the intelligence institution to tell “U.S. and non-U.S. individuals” of particular threats aimed toward “intentional killing, critical bodily harm and kidnapping.”

These directives are comparatively uncommon, however america is obliged to situation them, even to adversaries, and has finished so with each the Taliban in Afghanistan and the Iranian authorities prior to now yr. The warnings aren’t often made public except U.S. authorities assume the risk may impression Americans, which was the case in Moscow.

Mr. Putin, in each 2017 and 2019, thanked the U.S. authorities for offering info that had helped Russia foil terrorist assaults in St. Petersburg. However analysts say the same gesture could be unattainable within the acrimonious surroundings he has created since invading Ukraine.

America has been monitoring ISIS-Ok actions very intently in latest months, senior officers mentioned. In the midst of the monitoring, which has concerned digital intercepts, human informants and different means, American operatives picked up pretty particular details about plotting in Moscow, officers mentioned.

Specialists mentioned Russia’s intelligence providers have historically been centered on home terrorist threats emanating from separatist and spiritual extremist teams in Russia’s North Caucasus area. Giant terrorist assaults on Russian soil attributed to worldwide teams just like the Islamic State or Al Qaeda have been uncommon, and the nation’s home safety providers have much less expertise monitoring these threats and are much less expert at penetrating Central Asian extremist cells.

Within the days for the reason that assault, Moscow has returned the favor to Washington for providing the tip by claiming its warning ought to be handled as proof of potential American complicity.

Mr. Bortnikov, the F.S.B. director, mentioned on Tuesday that Islamist extremists alone couldn’t probably have carried out the assault. He blamed, amongst others, america.

Oleg Matsnev, Safak Timur and Aric Toler contributed reporting.