President Donald Trump fired back at former FBI director James Comey, who fretted over Republicans failing to defend federal law enforcement agencies and their investigation of the president’s 2016 campaign.

“Attacks on the FBI and lying about its work will do lasting damage to our country,” Comey wrote on Twitter. “How is he going to explain to his grandchildren all of the lies, the deceit, all of the problems he’s caused for this country?”

The president had a quick response, speaking in an interview with Fox and Friends host Brian Kilmeade aired on Thursday.

“How is he going to explain to his grandchildren all of the lies, the deceit, all of the problems he’s caused for this country?” he said.

Trump said that his decision to fire James Comey would go down in history as a “great service” for the country and the FBI.

“The FBI is great. I know so many people in the FBI, the FBI is a fantastic institution,” he said. “But some of the people at the top were rotten apples. James Comey was one of them.”

Asked if he would have a problem explaining his actions to his grandchildren, Trump chuckled.

“No,” he replied. “We’re doing a great job. Our country is coming back. Our country is respected again.”

Later Thursday morning, Trump reacted to Comey on Twitter.