Soon after explosions rang out on the morning of February 24th, internet connectivity dropped in Kharkiv, Ukraine’s second largest city, and the surrounding area. A quarter of users lost their connection. Kyiv, Luhansk and Mariupol soon experienced similar outages.

IODA, a research team at the Georgia Institute of Technology, an American university, is tracking these disruptions in two ways: by probing networks that automatically respond to the sender and by watching networks on the Border Gateway Protocol, a global routing system. They found that the responsiveness of Triolan, one of the main service providers in Kharkiv, plummeted in the early hours of the invasion.

Finding the cause of such outages can be tricky. Kyivstar, the country’s largest mobile provider, reported that its networks were underperforming because of a high volume of calls and texts. Blackouts may also occur when shelling destroys physical infrastructure.

But disabling the internet is also a tactic favoured by military leaders hoping to sow confusion. A breakdown in communication coupled with poor access to media and digital finances can have dire consequences. Vladimir Putin, Russia’s president, is no stranger to such tactics.

Distributed denial of service attacks, which work by flooding networks with huge amounts of traffic until they crash, have been on the rise since February 15th. The homepages of Oschadbank and PrivatBank, two big state-owned financial institutions, both went down on February 23rd. So did government websites, including those of the security services and foreign ministry. That evening a new sophisticated “wiper” malware, named HermeticWiper, attacked hundreds of computers. A timestamp on the software shows that it was first compiled in December, suggesting the move had been planned for months.

Ukraine is unlikely to suffer a complete internet outage. Before the Russian invasion, many of the country’s 2,000-odd internet providers prepared for attacks by diversifying network routes and equipping staff with satellite phones. Extra defences are now being built. Requests for volunteers are streaming in on hacker forums and the Ukrainian government is asking its citizens to help defend against the onslaught of cyberattacks. The battle against Russia will not only be fought on the streets. ■

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