Comey defends FBI's use of secret informants

Former FBI Director James Comey is defending the FBI's use of a secret informant in the Russia investigation, saying the practice is "tightly regulated and essential to protecting the country."

And he's criticizing the president and other Republicans for lying about the agency's work.

He tweeted Wednesday: "How will Republicans explain this to their grandchildren?"

President Donald Trump fired Comey last year amid the bureau's Russia investigation. The firing is now under investigation by the Justice Department's special counsel as possible obstruction of justice.

On Wednesday, Trump tweeted that the FBI's use of a government informant amounts to "one of the biggest political scandals in history."

Comey, a former Republican who now identifies as an independent, warned the GOP: "Attacks on the FBI and lying about its work will do lasting damage to our country."