The Ukrainian Military Intelligence (MIU) seized 100 gigabytes (GB) of classified data worth about $1.5 billion from the Russian company Center for Special Technologies, the MIU reported on Monday, Kyiv Independent reported.

The St. Petersburg firm, which has come under Ukrainian and international sanctions, manufactures Orlan reconnaissance drones, electronic warfare systems and other equipment used by the Russian military.

Orlan drones are widely used by the Russian forces invading Ukraine to adjust artillery fire and scout Ukrainian positions.

HUR allegedly obtained plans, patents and software for both existing and developing projects.

The agency said it gained access to the company’s “critically important” data on the defense industry “through effective cooperation with patriotic civil society representatives and the media community.”

“This is a significant blow to Moscow: these data are already being used to strengthen Ukraine’s defense capabilities and weaken the aggressor state,” the military department of Ukraine said.

In December, the media reported that a group of Ukrainian hackers with the support of the Security Service of Ukraine (SBU) attacked the critical infrastructure of the Russian utility company Rosvodokanal. The hackers allegedly deleted more than 50 terabytes (TB) of data and gained access to 1.5 TB.

The attack comes just a week after a massive Russian-linked cyberattack on Ukrainian phone operator Kyivstar caused internet and network outages across the country.