Two cybersecurity firms with a strong business presence in Ukraine—ESET and Broadcom’s Symantec—have reported tonight that computer networks in the country have been hit with a new data-wiping attack. The attack is taking place as Russian military troops have crossed the border and invaded Ukraine’s territory in what Russian President Putin has described as a “peacekeeping” mission.

The White House rapidly gathered evidence and blamed Russia for a cyberattack against Ukraine, the latest sign that cyber attribution is an increasingly crucial tool in the American arsenal.

Control of the internet is increasingly part of any modern conflict.

The FBI, NSA, and CISA warned that Russian state-sponsored intrusions will continue.