Ukraine Hit Yandex's AI Data Centres Twice in Two Days

A server hall inside a data centre. Yandex's struck facilities at Sasovo and Kaluga house tens of thousands of servers between them. Photo: Wil Weterings / Wikimedia Commons (public domain).

Ukraine has just done something it has never done before: hit Russia's data centres. Twice, in two days. And the targets weren't random — one of the sites struck reportedly houses the supercomputers that train YandexGPT, the flagship AI model of "Russia's Google."

On the night of October 7–8, drones slammed into Yandex's Sasovo data centre in the Ryazan region, southeast of Moscow, sparking a fire that forced the company to suspend operations at the site entirely. On the morning of October 9, a second strike hit Yandex's Kaluga facility southwest of Moscow, partly disabling it. Yandex itself called data centres the "iron heart" of its business — and that heart is now taking direct hits.

Whether the A100 supercomputers survived is the question no one can answer yet. Yandex declined to say.

The night Sasovo burned

The Sasovo attack was the first major strike on a Russian data hub since the war began, according to Reuters. The facility is one of Yandex's five large data centres and hosts tens of thousands of servers, the company said. The drone attack caused a fire; emergency services were on site; there were no casualties reported. "The data centre has stopped operating entirely, and some Yandex services may be unavailable to users," a Yandex spokesperson told AFP.

Yandex's cloud status page told customers the same story in drier language: problems with the electricity supply to one data centre "zone," recommendation to use other zones. Cloud customers who actually tried to fail over got uglier news. Alexander Savitsky, founder of the start-up dating app Pulse, which runs on Yandex Cloud with 8,000 users, told Reuters that none of his users had been able to access the service since Thursday — and his company could not even reach its backup database, getting an "internal error" message when trying to restore elsewhere. "We have no confirmation of actual data loss, but the situation is serious: the project represents three years of work," Savitsky said.

That line should chill anyone who keeps their data on someone else's computers. A backup you can't reach is just a prayer.

The supercomputers Russia can't replace

Here's what makes Sasovo more than a server fire. In 2021, Yandex said the site hosted two of its three supercomputers — clusters built around Nvidia A100 chips — used to train YandexGPT, one of Russia's leading generative AI models. When asked whether the supercomputers were affected by the attack, Yandex declined to say.

On October 8, the company said it was still assessing the damage: "The scale of the damage to the infrastructure is still being assessed. For the moment, we cannot confirm whether it is possible to restore the data center equipment in Sasovo." Read that twice. Yandex cannot confirm whether the equipment can be restored at all.

The stakes are bigger than one company's hardware. Western sanctions have strangled Russia's chip imports, and Sberbank — whose GigaChat competes with YandexGPT — has publicly said Russian AI developers lag their US and Chinese counterparts by six to nine months, with sanctions-driven chip-import difficulties the main bottleneck. If the Sasovo fire touched the training cluster, those A100s cannot be easily replaced. Russia's flagship AI programme would be set back years, and nobody outside Yandex knows yet.

Day two: Kaluga, and the FP-1

The second strike came on the morning of October 9. Yandex said its Kaluga data centre, southwest of Moscow, was struck by Ukrainian drones and partly put out of action. Ukrainian arms maker Firepoint said Kyiv had used its FP-1 one-way attack drones against what it called Yandex's biggest data centre, and that several modules had been completely knocked out of action.

Yandex said it was "facing a difficult challenge to maintain its services," adding that teams were working day and night. "Right now this is our most important task, but unfortunately it is not an easy one," the company said in a statement.

The FP-1 detail matters beyond the weapon name. These are one-way attack drones reaching targets deep inside Russia — Sasovo is southeast of Moscow, Kaluga southwest. Ukraine's long-range strike reach now demonstrably covers Russia's digital core, and the Kaluga strike happened a day after the first, which says this wasn't opportunistic. It was a campaign.

"Our tit-for-tat response" — and the confirmation fog

Ukrainian President Volodymyr Zelensky has been open about the logic. Asked about the Sasovo strike on October 8, he said: "We always respond in mirror-like fashion. You all know, they have been hitting and continue to hit our data centres. We are responding. I can't share all the details."

Reuters reported that Zelensky confirmed on Friday that Ukrainian drones had struck the Kaluga data centre in what he called "our tit-for-tat response." The Kyiv Independent, however, wrote that Ukraine has not publicly confirmed responsibility for the Kaluga attack. The tension is worth flagging: Reuters attributes a confirmation; Ukraine's own English-language press doesn't see one. What isn't disputed is the sequence — Russia has been hammering Ukrainian data centres and telecom infrastructure for weeks, including targets in central Kyiv, forcing some Ukrainian data centres to suspend operations. One attack knocked 100,000 households offline.

Ukraine's digital minister told Reuters last month that the country is moving its digital infrastructure underground. There is a vulnerability-assessment angle here nobody else is doing: Kyiv hardened its data centres underground, while Yandex's flagship facilities sat exposed hundreds of kilometres from Ukraine — and Yandex is now reportedly discussing moving facilities to "friendly" countries. One side dug down. The other is looking for a new postcode.

The "iron heart" stops — what went down

Yandex's October 9 statement is worth quoting at length, because it shows what a tech company says when its infrastructure is on fire: "Data centers are the iron heart of Yandex. Their operation is critical for services that have become part of people's everyday lives. Millions of users check traffic and plan routes, listen to music, watch movies, order groceries and get answers to their questions. Our technology helps hundreds of thousands of companies run their businesses."

Thursday's outage reports mapped that out in practice: real-estate aggregator Cian, book portal Litmarket, the websites of Russian Railways and football club Spartak Moscow all reported technical issues. A state-owned bus company in the Moscow region said online ticket sales were unavailable because of the "temporary shutdown of a data centre." The monitoring service Detector404 logged 58,268 user complaints in a single day. In Kaluga, the regional governor said nine people were injured in drone attacks on the region.

The market noticed too. Yandex shares were the biggest faller on the Moscow exchange on Friday, down about 4%. Maryana Lazaricheva, head of equity research at T-Investments, told Reuters the strikes risk lost revenue across segments and hit Yandex's extensive B2B client base: "The risks involve not only the potential temporary unavailability of Yandex services and lost revenue in specific segments but also the company's extensive base of B2B clients." The company could redistribute load to its three remaining data centres, she noted — "but if the chain of attacks continues, this possibility vanishes, which could lead to even more severe consequences."

That conditional — if the chain continues — is the whole story. Yandex struck a deal with other cloud providers to let clients move data and services quickly. But two of its five data centres have been hit in two days. The arithmetic of "redistribute to the other three" only works if the other three stay standing.

Our take: this is a new front, not an incident

War reporters will file this as Ukraine hitting Russian infrastructure. But for the tech world, it's the moment the war on data centres went both ways — and the AI infrastructure angle is being dangerously undercovered. Competitors are writing about outage maps and share prices. Nobody is doing the vulnerability math: Russia's flagship AI training hardware was sitting in a facility that a one-way drone could reach, in a war where both sides have been expanding drone campaigns across energy, refineries, ports, warehouses and now data centres all year.

The uncomfortable question: if Russia's sanctions-strangled AI programme just lost two A100 clusters it cannot replace, Ukraine didn't just hit a data centre. It hit the one Russian industry where the gap with the West was already 6–9 months and widening. And Yandex's silence on the supercomputers is the loudest part of this story.

Frequently asked questions

Did Ukraine officially claim the strikes? Zelensky spoke of responding "in mirror-like fashion" after the Sasovo strike and Reuters attributed a "tit-for-tat response" confirmation to him after Kaluga — but the Kyiv Independent notes Ukraine has not publicly confirmed responsibility for the Kaluga attack. The claims conflict; treat them with that tension intact.

Were the AI supercomputers damaged? Unknown. Yandex hosted two of its three Nvidia A100 supercomputers at Sasovo, declined to say whether they were affected, and later said it could not confirm whether the equipment can be restored at all.

Why would Ukraine target Yandex? Ukraine's stated logic is retaliation: Russia has been attacking Ukrainian data centres and telecom infrastructure for weeks. Zelensky's framing is explicit — "they have been hitting and continue to hit our data centres. We are responding."

Could Russia's AI programme be set back? Possibly, if the training clusters were destroyed. Sberbank has said Russian AI developers lag US and Chinese counterparts by 6–9 months because sanctions block chip imports — replacement A100-class hardware would be extremely difficult to obtain.

By Daniel Rao

Daniel Rao covers AI infrastructure, cybersecurity and the business of the frontier labs for TechPulse USA.

Sources

Reuters (Oct 8 and Oct 9 reporting, via Straits Times, CNA, NDTV and Daily Sabah syndication); AFP via Bangkok Post; the Kyiv Independent; TASS via newsatw. Direct quotes from Yandex company statements and President Volodymyr Zelensky as reported by Reuters; Alexander Savitsky, founder of Pulse; Maryana Lazaricheva, head of equity research at T-Investments.

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