A second Ukrainian drone strike puts part of Yandex's Kaluga data centre out of service

Yandex said on Friday that a Ukrainian drone strike had partly disabled its data centre in the Kaluga region, southwest of Moscow. The company said part of the site's infrastructure had been taken out of service. A day earlier, a strike shut its hub at Sasovo, in the Ryazan region, one of five large centres, where two of the three supercomputers used to train the company's AI model are housed. Yandex said on Thursday it could not yet say whether the Sasovo equipment could be restored. No employee was injured at either site.

Ukrainian arms maker Firepoint said Kyiv had used its FP-1 one-way drones against what it called Yandex's biggest data centre, and that several modules had been knocked out. The Kaluga regional governor said nine people were injured in a drone attack on the city's infrastructure. Yandex told Tass that some functions of its AI chatbot were temporarily unavailable, and that its smart-home devices might also fail. The company said its centres were critical to normal service and that it was very difficult to predict when they would be back. Teams were working day and night. It was not a simple task, the company said.

What sits in these buildings

Yandex runs Russia's most-used search engine and the apps millions of people open for taxis, food orders, maps, music and film. It is also one of the few firms in the country with the power and the chips to train large models. Five large data centres carry that load. Losing Sasovo entirely, and part of Kaluga a day later, is not a symbolic hit on a logo. It is a cut in the physical plant that serves both the consumer apps and the training runs.

The company said on Friday it was facing a difficult job keeping services up. A dating-app firm that relies on Yandex cloud told reporters its users could not get in and that it feared for backup data. That is the second-order effect. Russian businesses that rent capacity rather than build their own have nowhere domestic to move if two of the five hubs are degraded at once. Foreign clouds are not a ready substitute under the current sanctions and routing rules.

Why these targets, and why now

The strikes follow Ukrainian attacks on data hubs inside Ukraine and sit inside a week in which Russian bombs killed dozens of civilians, including the strike on two buses in Kramatorsk. Kyiv has described the data-centre hits as an expansion of the target set after Moscow hit Ukrainian digital infrastructure. Firepoint's claim names the weapon, the FP-1, and the aim, modules rather than a single server room. Yandex's own statement is the better source for damage: part of Kaluga is out, Sasovo is suspended, staff are alive.

The governor's injury count of nine is not a Yandex staff count. Yandex was explicit that none of its employees were hurt. The nine are people the region classes as injured in the wider attack on city infrastructure. Those two figures can both be true.

The number that will show the outage

Search still loading on a phone does not mean the centres are fine. Yandex can shift traffic, serve cached pages and degrade features without a total blackout. The signals it has already named are the ones to track: chatbot functions down, smart-home devices unreliable, and a cloud customer locked out of its own backup. If those spread to maps and taxis, the outage has left the training cluster and entered the daily services. The company has not given a restoration date. It has said it cannot predict one.