The Kremlin has voiced "alarm" at a report in The New York Times that said the United States was preparing a series of covert counter cyberstrikes on Russian networks.
U.S. intelligence officials have said that Russia was probably behind the massive hack known as SolarWinds that hit large swaths of the public and private sectors last year, and which experts say may constitute an ongoing threat. Russia has denied the accusations.
White House national-security adviser Jake Sullivan said last month that Washington would respond to SolarWinds in "weeks, not months."
The March 7 report in the U.S. newspaper quoted unnamed officials as saying that Washington was planning a series of covert counterstrikes on Russian networks in retaliation to the SolarWinds hack, with the first major move expected in three weeks' time.
It said the clandestine actions would be intended to be obvious to Russian President Vladimir Putin and his military intelligence, but not to the rest of the world.
"This is alarming information," said Kremlin spokesman Dmitry Peskov. "This would be pure international cybercrime."
"The fact that the newspaper doesn't rule out that the American state could be involved in cybercrime definitely causes us concern," Peskov added.
The report came as the U.S. government warned of a major new cyberattack targeting Microsoft servers that has been linked to China.
The Cybersecurity and Infrastructure Security Agency issued an urgent notice on March 6, calling on companies and government agencies to install critical software updates that were described as an "emergency patch release."
White House spokeswoman Jen Psaki called the alleged Chinese hack an "active threat."
The article in the U.S. newspaper said that the scope of the Chinese attack prompted U.S. officials to consider potential retaliation against Beijing as well.
It noted that such a move would put the United States in the position of engaging in a dual cyberconflict with the two countries that are its biggest nuclear-armed adversaries.