Ukrainian Drones Hit a Yandex Hub Housing Two Supercomputers That Train Russia's Leading AI

A drone strike on Thursday set fire to a Yandex data center in Sasovo, in Russia's Ryazan region, about 300 km southeast of Moscow. Yandex shut the whole site down. The building also houses two of the supercomputers Russia's biggest tech company uses to train its AI.

Yandex told CNBC that nobody was hurt, that emergency services were on site and that some services might not work for a while. Sasovo is one of the five data centers the company runs.

A cloud zone goes dark

The damage spread quickly. Internet monitor NetBlocks saw Yandex's network connectivity fall to around 70% of normal, The Record reported. Yandex said on Telegram that it had moved workloads to other facilities, but customers could only create new cloud resources in limited ways and were told to move workloads elsewhere.

That advice looks permanent for now. According to The Register, Yandex Cloud's ru-central1-b availability zone is down because of the fire, and the company says it won't be able to restore it any time soon. A later Reuters report said it was unclear whether the data center could be restored at all.

Compute, networking, storage and databases on Yandex Cloud all went down. Users also reported trouble with Yandex Disk, Documents, Mail, Pay and Market. Businesses running on the same infrastructure, including Russian Railways, Ozon, Wildberries and T-Bank, were named among those affected.

The machines behind YandexGPT

The detail most wire stories underplayed is what sits inside the building. Tom's Hardware reports that the Sasovo campus holds two of Yandex's three Nvidia A100 supercomputers. They are used for AI work, including training YandexGPT.

One of them, Chervonenkis, ranked 19th on the Top500 list in 2021 with 21.53 petaflops of FP64 performance. It has since slipped to around 101st. The other is Lyapunov. The third machine, Galushkin, is in Vladimir.

Yandex hasn't said whether either system survived. Replacing them would be hard. Sanctions already block Russia from buying new Western AI hardware, so a lost A100 cluster cannot simply be swapped for something newer.

Nobody has claimed it

Ukraine hasn't publicly claimed the strike. Russia's Defense Ministry said air defenses shot down Ukrainian drones over several regions overnight, Ryazan among them, and local officials first said there was no damage. Photos on Telegram later appeared to show fire at the Sasta machine-tool plant, which hosts the campus. Britain has sanctioned the plant since 2024 over its ties to the defense sector.

The hit follows a September in which Moscow went after Ukrainian data centers and telecom operators, including MiroHost, Parkovy and Data Group. On 23 September, fixed-line outages hit around 100,000 households in the Kyiv area. Zelenskyy has described strikes on energy and infrastructure as reciprocal pressure heading into winter.

Big compute campuses were already political fights at home, as the nearly $200B in US data center projects blocked or delayed by local communities shows. Sasovo shows they are now military targets too, and losing one can take a country's AI training capacity down with it.

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