"Only Russia's senior-most officials" could have authorized these activities, given the scope and sensitivity of these efforts, according to the statement.
In July, WikiLeaks leaked nearly 20,000 emails from top Democratic National Committee officials, causing turmoil just ahead of the Democrats' political convention. Since then numerous hacks and leaks have been linked to Russia.
"These thefts and disclosures are intended to interfere with the US election process," said today's official U.S. statement.
Kremlin spokesman Dmitry Peskov called U.S. allegations against the Russian government of involvement in hacking attacks on US servers and organizations "nonsense," according to the Russian state news agency, Interfax.
He also blamed the U.S. for what he claimed were similar attacks against the Kremlin.
U.S. officials today said that in most cases the recent "scanning and probing" of election-related systems originated from servers operated by a Russian company. However, the U.S. said that it's not in a position to attribute these attacks to the Russian government.
The recent hacks were "consistent" with the methods and motivations of Russian-directed efforts, said today's statement.
Russians have used similar tactics and techniques across Europe and Eurasia to influence public opinion there, according to officials.
For months sources and security experts have been blaming the Russian government for the recent hacks against the U.S.
There had been back-and-forth within the government over whether to release a public statement because of concern it might escalate the situation, according to sources familiar with the deliberations.
"The President has made it clear that we will take action to protect our interests, including in cyberspace, and we will do so at a time and place of our choosing. Consistent with the practice we have adopted in the past, the public should not assume that they will necessarily know what actions have been taken or what actions we will take," according to a senior administration official.
Today's pronouncement comes a time of high tension between the U.S. and Russia. Earlier this week, the U.S. government announced that it was suspending all Syrian peace talks with Russia over frustrations with Moscow and its inability to live up to commitments to a cease-fire agreement.
-Alex Mallin contributed to this story.