A major Yandex data center in Sasovo, in Russia's Ryazan region, lost power Thursday after a reported Ukrainian drone strike, disrupting Yandex Cloud and knocking several Russian websites offline, The Record reported. Tom's Hardware said the site houses two of the AI supercomputers Yandex uses to train its language models.

What Happened

The data center sits inside a machine-tool plant that has been under British sanctions since 2024 over its ties to Russia's defense sector, according to The Record. A fire was reported at the plant, and it is not clear whether the factory or the data center was the intended target. Tom's Hardware, citing Reuters and Meduza, described a large fire that forced Yandex to shut the facility down.

Ukraine's military has not commented. Russia's Defense Ministry said air defenses intercepted Ukrainian drones over Ryazan and other regions, and local authorities reported no damage.

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Yandex acknowledged a power outage in a Telegram post without connecting it to the strike. The company warned that the ability to create new resources in its cloud may be limited and advised customers to move workloads elsewhere. Tom's Hardware said Yandex recommended switching to other availability zones and maintained that its key consumer services stayed up.

Services Hit

The Record said affected Yandex Cloud services included computing, storage and databases, and that Yandex Disk, Yandex Documents and several other Russian websites became unreachable. Internet monitor NetBlocks showed connectivity on Yandex's network falling to about 70% of normal levels.

Tom's Hardware reported that users also had trouble with Yandex Mail, Pay and Market, and that Russian Railways, the 1C business software platform and corporate systems at T-Bank, Ozon and Wildberries were disrupted, citing Meduza. Outage tracker Detector404 logged 58,268 complaints in 24 hours. State outlets RIA Novosti, Vesti and Interfax also went down after what RBC described as an attack on an "infrastructure partner."

Why It Matters

Sasovo is one of Yandex's five major data centers and holds tens of thousands of servers, according to Tom's Hardware. It is home to two Nvidia A100-based supercomputers, Chervonenkis and Lyapunov, which Yandex has used to train models including YandexGPT. Chervonenkis, rated at 21.53 petaflops in double-precision math, ranked 19th on the Top500 list in 2021 and would sit around 101st today. Yandex has not said whether either system was damaged.

Replacing that hardware would be difficult. Western export controls block Russian buyers from Nvidia's newer accelerators, and Tom's Hardware said sanctions already prevent Yandex from upgrading Chervonenkis. Its third supercomputer, Galushkin, is in Vladimir.

The outage also shows how much of Russia's online economy runs on Yandex Cloud, one of the country's largest domestic cloud platforms, and how a single site can ripple into banks, retailers and rail services.

A Widening Fight Over Data Centers

The strike follows a Russian campaign against Ukraine's digital infrastructure. The Record said Russian strikes late last month damaged at least six Ukrainian data centers, including facilities run by MiroHost, Parkovy, Data Group, Utels and Pautina, and that a Sept. 23 attack cut fixed-line internet for about 100,000 households in and around Kyiv. Tom's Hardware counted data centers belonging to at least eight Ukrainian companies damaged or destroyed since Sept. 23.

Ukraine is moving some digital infrastructure underground, Tom's Hardware said, while Russian companies are discussing deployments in countries Moscow considers friendly.

What to Watch

The main questions are how long Yandex Cloud capacity stays constrained, whether Yandex discloses the condition of its supercomputers and whether either side extends strikes to more data centers.