Sasovo first, then Kaluga
The Kaluga strike came a day after a Ukrainian attack shut down Yandex's data hub in Sasovo, southeast of Moscow. Reuters reported it was the first major attack on a Russian data hub since the start of the war.
Yandex said the Sasovo strike caused a fire that forced it to suspend operations at the site, which houses tens of thousands of servers.
The Sasovo facility is one of Yandex's five large data centers, and the stakes are particularly high there: the company said in 2021 that the hub hosted two of its three supercomputers, built around Nvidia A100 chips, used to train its YandexGPT large AI model.
Yandex declined to say whether the supercomputers were damaged.
Ukrainian arms maker Firepoint said Kyiv used its FP-1 one-way attack drones in the Kaluga strike, which it described as targeting Yandex's biggest data center, adding that several of its modules had been completely knocked out of action.
Services stumble across Russia
Yandex acknowledged it is facing a difficult challenge to maintain its services, which millions of Russians use daily for navigation, music, movies, and food orders, alongside cloud computing services many businesses depend on.
The company said its core consumer services were not affected and that it was restoring services, but Yandex Cloud warned customers of power-supply problems in one data center zone and recommended using others.
The disruption spilled across Russia's internet. Independent outlet Meduza reported that Russian users had trouble reaching the Ivi streaming platform, T-Bank's banking app, and the Russian Railways website.
On Thursday, the real estate aggregator Cian, book portal Litmarket, and the websites of Russian Railways and football club Spartak Moscow also reported technical issues.
Alexander Savitsky, who runs the dating app Pulse with about 8,000 users, told Reuters his company had been unable to access its service since Thursday.
He said the firm could not reach its backup database in Yandex Cloud and was getting an internal-error message when trying to restore it elsewhere — three years of work now at risk.
A widening front: data centers as targets
Ukraine framed the strikes as retaliation. Ukrainian President Volodymyr Zelenskyy said the attacks were a response to Russia's own campaign against Ukrainian data hubs: Russia has spent the past month striking Ukrainian data centers and telecommunications infrastructure, including targets in central Kyiv.
The back-and-forth has gradually spread the drone war across the economy, from energy facilities and refineries to ports, e-commerce warehouses, and now data centers — with AI compute itself becoming a target. Yandex's shares fell on the Russian exchange after the attacks.
By Hamza Faisal
