The first major regional telecommunications blackout in Ukraine, since Russia’s invasion of the country a week ago, was reported Thursday.

At 8:23 p.m. in Ukraine, Eastern European Standard Time, internet service tracker NetBlocks tweeted that it has confirmed that a telecommunications blackout has just been registered throughout Sumy Oblast in northeastern Ukraine.

The blackout was reported as “residents report massive blasts at the thermal power plant and electrical substation that turned the sky ‘yellow and red’ for miles,” NetBlocks tweeted.

“This is the largest regional telecoms black out that we’ve tracked since the beginning of the conflict,” said Alp Toker, director at NetBlocks, in a message to VentureBeat.

Telecoms service in Mariupol has been faltering and went out in a few stages, but the situation in Sumy Oblast “is a single discrete event,” Toker said. “It looks serious.”

Sumy Oblast has a population of just over 1 million people. Its central city, Sumy, is located about 336 kilometers (208 miles) to the east of Ukraine’s capital, Kiev.

Until this point, Ukraine’s communications infrastructure had not been severely affected since the start of the Russian attacks.

The report of blasts at a power plant would seem to rule out the role of cyberattacks in the outage, though there wasn’t any information immediately available to determine for sure.

Other Ukrainian cities including Kyiv and Kharkiv have experienced internet disruption at different points, after Russia’s unprovoked attacks against Ukraine, but have not faced a total blackout in service at any time, NetBlocks reported previously.

Faltering strategy

Russia’s strategy so far has been “disastrous,” and the Russian military is now resorting to heavy armament and explosives to cause destruction in civilian-concentrated areas, ContraForce CEO Stan Golubchik said in an email to VentureBeat on Wednesday.

Russia has a history of being “very destructive when wars aren’t going its way,” said Eric Byres, CTO of aDolus Technology, on Wednesday.

The “massive destruction” unleashed on Grozny in 1994 to 1995, and once again from 1999 to 2000, are examples, he said.

Alex Bornyakov, deputy minister of digital transformation for Ukraine, told TechCrunch this week that Ukraine has “multiple levels of backups” for its communications infrastructure. As one potential element, a shipment of Starlink satellite dishes was sent to the country this week by SpaceX CEO Elon Musk.

“Important warning: Starlink is the only non-Russian communications system still working in some parts of Ukraine, so probability of being targeted is high. Please use with caution,” Musk tweeted Thursday.

In terms of using with caution, “Turn on Starlink only when needed and place antenna away as far away from people as possible,” Musk tweeted. “Place light camouflage over antenna to avoid visual detection.”

During the Russian assault, cyberattacks have not been known to have been used to cripple Ukraine’s communications infrastructure, as many had feared. That had allowed phone and internet service, critical to Ukraine’s defense and morale, to continue functioning.

Experts told VentureBeat on Wednesday that there was a strong likelihood for a greater impact on communications systems going forward. “The potential for both cyber and kinetic attacks to escalate remains,” said Danielle Jablanski, an OT cybersecurity strategist at Nozomi Networks, on Wednesday.