Testifying before a congressional panel on Wednesday, Jeanette Manfra, the Homeland Security Department's acting deputy undersecretary of cyber security, disclosed the number publicly for the first time.
"As of right now, we have evidence that election-related systems in 21 states were targeted," Manfra (pictured below) told the Senate Intelligence Committee.
Both Trump and Russia have denied allegations of meddling in the 2016 election and collusion between his associates and the Kremlin while the issue is being investigated.
Manfra, however, refused to reveal which states were targeted. Last year, Arizona and Illinois confirmed that their voter registration systems had been targeted.
Access Hollywood tape a distraction
Jeh Johnson, who led the Homeland Security Department until the end of the Obama administration, also told a separate panel -- the House Intelligence Committee -- that the department’s warnings at the time went unnoticed due to the emergence of a 2005 tape, in which Trump brags about sexually assaulting women.
The embarrassing video was recorded while Trump was on a bus with former "Access Hollywood" host Billy Bush.
Trump’s late-night apology for the remarks failed to quell the unprecedented controversy over his comments, which include explicit language and boasting sexual harassment of women, Presstv reported.
Asked why the Homeland Security did not do more to warn the public, Johnson said, "We were very concerned that we would not be perceived as taking sides in the election, injecting ourselves into a very heated campaign."