Washington was able to determine Russia's involvement based on the "signature" of the attacks, which a government official told NBC News hackers may not have realized they left behind. The official used an analogy of a criminal investigation of a home invasion: the Russians might "shimmy down the chimney," the Chinese "would kick the door down" and the North Koreans "would build a tunnel and flood the chamber."
Rep. Adam Schiff, D-Calif., commended the decision to name Russia and called for a more coordination with European allies that "deters further meddling."
"All of us should be gravely concerned when a foreign power like Russia seeks to undermine our democratic institutions, and we must do everything in our power to guard against it," said Schiff, a ranking member of the House Permanent Select Committee on Intelligence.
Sen. Dianne Feinstein, D-Calif., vice chairman of the Senate Intelligence Committee said the Russian hacking of the U.S. election system is "intolerable" and that the U.S. needs to develop a strong response.
Sen. Cory Gardner, R-Colo., said the Obama administration's "strategic patience policy has failed" and that he plans to introduce a bill that would impose sanctions on Russia's cyber criminals. The bill would resemble similar provisions within the North Korea Sanctions and Policy Enhancement Act.
"Russia's interference with American democracy is a direct threat to our political process, and it may only be the tip of the iceberg. It is imperative that Russia's behavior is met with strength in the form of aggressive sanctions to show the world that its cybercrimes will not be tolerated," said Gardner, chairman of the Senate Foreign Relations Subcommittee on East Asia, the Pacific, and International Cybersecurity.
Friday's news comes after thousands of internal emails between Democratic officials were dumped by WikiLeaks ahead of the party's national convention this summer.
Last month, Putin called the hacking of Democratic National Committee emails a public service, but denied accusations that his government was involved in the email hack.
"The important thing is the content that was given to the public," he said in an interview with Bloomberg.