The whistleblower famous for releasing the "Pentagon Papers" to The New York Times during the Vietnam War called for more federal employees to blow the whistle on President Donald Trump during an interview with MSNBC's Ari Melber.
Daniel Ellsberg praised the whistleblower -- while warning her or his life may be in danger.
"I nevertheless congratulate this whistleblower on the success that they’ve had so far in getting that information out and on the courage that she showed or he showed in taking this on," Ellsberg said.
"Even following the rules, to challenge a president for wrongdoing is not safe, either physically or legally, and I hope that the Democrats in Congress, in the House, will take every precaution to keep her identity or his identity secret from the president," he continued.
Ellsberg as put Trump's conduct into historic context.
"I don’t think any of the previous presidents put a target on the back of the whistleblower, calling to armed and violent constituents in some cases to say that that person should be treated before trial, before due process, anything else, as a spy or a traitor," he explained.
"He is calling for physical attack, I would say I think that’s an impeachable offense or criminal offense in itself," Ellsberg concluded.
"What do you, Daniel Ellsberg, say to these now two whistle-blowers out there tonight?" Melber asked.
"I congratulate them. What I would like to speak to is the people who, like me, kept their mouths shut when they knew the president was doing wrong," he replied.
"Do you think there are others in the Trump Administration?" Melber asked.
"I’m absolutely sure," Ellsberg replied. "For one thing, the whistleblower revealed there were more than a dozen people on that program, on that call. This president is turning out to be a domestic enemy of the Constitution. Every one of them should be a whistleblower right now. And it’s not too late.