Hackers successfully breached more election systems ahead of last year’s White House race than previously acknowledged, according to a new report.

The U.S. intelligence community conceded in January that hackers had targeted systems associated with last year’s election, and a classified document leaked in June indicated that VR Systems, a Florida-based company that sells electronic voting services and equipment, was breached before the 2016 race.

“Beyond VR Systems, hackers breached at least two other providers of critical election services well ahead of the 2016 voting,” The New York Times reported Friday, citing current and former intelligence officials speaking on condition of anonymity.

The sources declined to identify the affected companies, and the report did not state whether the hacks had an impact or to what degree. Nonetheless, the newly disclosed cyberattacks provides new details about the extent of attempts to interfere in last year’s election.

While The Times report doesn’t identify any suspects thought responsible for the pair of newly disclosed election hacks, the U.S. intelligence community has attributed past election-related cyberattacks to Russian President Vladimir Putin and Moscow’s military intelligence agency, G.R.U.

The U.S. Office of the Director of National Intelligence formally accused Moscow of meddling in this race shortly before President Trump took office Jan. 20 and said in an unclassified report that “Russian intelligence obtained and maintained access to elements of multiple U.S. state or local electoral boards.”

An intelligence document leaked in June, meanwhile, indicated that the National Security Agency believed Russian hackers had successfully infiltrated VR Systems, making the Florida vendor the first firm of its kind explicitly identified as one of Moscow’s alleged victims.

Russian actors failed to compromise any election systems directly involved in vote tallying, the January report said. Speaking to the Times, however, an election monitoring official warned that other systems were equally critical.

“What people focus on is, ‘Did someone mess with the vote totals?’” said elections specialist Susan Greenhalgh, “What they don’t realize is that messing with the e-poll books to keep people from voting is just as effective.’”

The Kremlin has denied meddling in last year’s election, and its alleged involvement remains the subject of ongoing probes in the House, Senate and Justice Department.