Former President Bill Clinton said he isn't sure whether foreign countries tampered with the 2016 presidential election results.

"We've got a real serious problem about this cyber terrorism," Clinton said in a Friday preview of an interview with CBS. "They could go way beyond fixing the elections and those problems will happen faster if we allow our elections to continue to be tampered with by others."

"I don't know. I don't know," Clinton responded, when asked whether he thought there was any "tampering in 2016 with results."



WATCH: Former President Bill Clinton is tackling fictional terrorism in a new novel. He co-authored the book "The President is Missing" with best-selling writer James Patterson.



He spoke to @CBSSunday's @MoRocca: https://t.co/h3jI1Mt8XV pic.twitter.com/e7UN71yXms — CBS This Morning (@CBSThisMorning) June 1, 2018



Senate Democrats have criticized Department of Homeland Security Secretary Kirstjen Nielsen for not doing enough to help states and localities protect election infrastructure after a March 10 report that Russians tried to attend a Democratic convention in Texas.

But DHS announced on March 26 it had hired Matt Masterson, the former chairman of the Election Assistance Commission, to assist authorities to coordinate their cybersecurity efforts ahead of the 2018 midterm elections.

In 2016, Russian agents attempted to break into 21 state election systems.

In another clip released Thursday, Clinton addressed Sen. Kirsten Gillibrand's argument that he should have resigned from office over his affair with White House intern Monica Lewinsky and his attempts to cover it up.

“You have to ... really ignore what the context was,” Clinton said about Gillibrand, D-N.Y. “But, you know, she’s living in a different context. And she did it for different reasons. So, I — but I just disagree with her.”

Clinton's full interview, given to promote his new political thriller novel, "The President is Missing," will air Sunday.