The EU and NATO condemned Russia's "malicious cyber campaign" against Germany and Czechia in public statements on May 3.
Earlier in the day, Germany blamed Russian-backed hackers for a cyberattack against members of the German Social Democratic Party (SPD) last year and promised to respond.
Separately, Czechia accused the same Russian-linked group, known as APT28, of targeting unspecified Czech institutions.
The European Council's press service said that the hacking campaign "shows Russia’s continuous pattern of irresponsible behavior in cyberspace, by targeting democratic institutions, government entities, and critical infrastructure providers across the European Union and beyond."
"This type of behavior is contrary to the U.N. norms of responsible state behavior in cyberspace, such as impairing the use and operation of critical infrastructure."
In a public statement, NATO expressed "concern that the same threat actor (APT28) targeted other national governmental entities, critical infrastructure operators, and other entities across the Alliance, including in Lithuania, Poland, Slovakia, and Sweden."
"We strongly condemn malicious cyber activities intended to undermine our democratic institutions, national security, and free society," the statement continued.
Russia's military intelligence agency, also known as GRU, has already been linked to numerous cyberattacks in Ukraine and elsewhere.
The Security Service of Ukraine (SBU) said that a GRU-backed group called SandWorm was responsible for a large-scale hacking attack against the Kyivstar telecommunications provider in December 2023.