Cyber attack on U.S. may have begun before Spring

Russia's alleged hacking of U.S. government agencies may have started earlier than last Spring - as previously thought.

That's according to Democrat Mark Warner on Wednesday (December 31) who's Vice-Chair of the Senate Intelligence Committee.

The attack, only made public earlier this month, used the U.S. tech company SolarWinds as a springboard to penetrate government networks for months, as well as critical infrastructure entities and private companies.

Once inside hackers were able to monitor internal emails at some of the top federal agencies, including the Treasury.

Warner told Reuters there was no evidence that classified government secrets had been compromised, but investigations are still ongoing:

"We're still getting information from classified sources, so I'm talking to people in the private sector side. I think it's safe to say that it may have started even earlier than March or April and that the initial burrowing in may have started earlier but the collection period did start calendar year 2020."

Senior U.S. officials and lawmakers have accused Russia of being behind the attack, a charge the Kremlin denies.

While, U.S. President Donald Trump has suggested China might be responsible.

Whichever actor is to blame, Warner said gaps in U.S. and international law made it harder to track and crack down on security breaches.