Cyber attack on U.S. government may have started earlier than initially thought - U.S. senator

FILE PHOTO: U.S. Senator Mark Warner (D-VA) addresses reporters during a break in the fourth day of the Senate impeachment trial of U.S. President Donald Trump at the U.S. Capitol in Washington, U.S., January 24, 2020. REUTERS/Erin Scott/File Photo

WASHINGTON (Reuters) - The unprecedented cyber attack on U.S. government agencies reported this month may have started earlier than last spring as previously believed, a U.S. senator involved in cybersecurity said on Wednesday.

U.S. investigators originally thought that the attack on government agencies and private industry targets began in March or April, including breaches of Treasury, State, Commerce and Energy Departments. State-backed Russian hackers were identified as the suspects. Russia has denied involvement.