Former director of National Intelligence James R. Clapper Jr. warned Sunday that the nation’s institutions are being undermined by President Trump after his decision last week to fire FBI Director James B. Comey.

Citing Russian influence in the U.S. election, Clapper told CNN’s Jake Tapper on “State of the Union” that outside forces were responsible for weakening the U.S. government. He also added that “our institutions are under assault internally.”

“Internally from the president?” Tapper asked.

“Exactly,” said Clapper. “I think the Founding Fathers, in their genius, created a system of three coequal branches of government and a built-in system of checks and balances. And I feel as though it’s under assault and eroding.”

Clapper’s remarks reflect a growing alarm among policymakers and legal experts who say Trump has undercut the credibility of the FBI and its independence, at a time when the agency is investigating alleged links between Trump’s campaign and Russian officials.

Former Director of National Intelligence James Clapper listens to a question during his testimony before the Senate Judiciary Committee subcommittee hearing on Russian interference in the 2016 election. (Bill O’Leary/The Washington Post)