The SolarWinds hack has been formally blamed on Russia.

Today, the Biden Administration announced a series of sanctions against Russia for various activities, including, but not limited to, election interference, cyber attacks, offering “bounties” to Taliban soldier for US troops, and the occupation of Crimea. While rumors and reports have circulated since the infamous SolarWinds breach of various US federal agencies, this is the first time the US government has laid any formal blame against the Russian government.

“Russian Foreign Intelligence Service (SVR) actors (also known as APT29, Cozy Bear, and The Dukes) frequently use publicly known vulnerabilities to conduct widespread scanning and exploitation against vulnerable systems in an effort to obtain authentication credentials to allow further access,” an advisory from the Federal Bureau of Intelligence, the Department of Homeland Security and National Security Agency said of the SolarWinds breach. “This targeting and exploitation encompasses US and allied networks, including national security and government-related systems.”

“When [President Biden] spoke to [President Putin] this week,” US National Security Adviser Jake Sullivan told reporters, “he said, ‘I told you that I was going to look into this, I made a determination that Russia has, in fact, conducted these actions, and I’m a man of my word, I am ready to respond, but I’m not looking to escalate. I’m looking to provide proportionate responses, and I believe that it is in our interest to find a stable and predictable way forward in this relationship.'”

“We have no desire to be in an escalatory cycle with Russia,” an official told reporters, reaffirming the administration’s stance. “We intend these responses to be proportionate and tailored to the specific past activities, past actions that Russia has taken. We have indicated that we seek a stable and predictable relationship going forward.”

The US Ambassador to Russia, John Sullivan, has been summoned to Moscow for a discussion with Russian government officials on the sanctions. According to Russian foreign ministry spokeswoman Maria Zakharova, a response to the sanctions will be “unavoidable.”