WATCH: Cliff Sims' lawyer says Trump instructed his campaign to go after the former White House aide
President Donald Trump delivers remarks at the American Cemetery of Suresnes, outside Paris, as part of Veterans Day and the commemorations marking the 100th anniversary of the 11 November 1918 armistice, ending World War I, Nov. 11, 2018. (DOD Photo by Navy Petty Officer 1st Class Dominique A. Pineiro)

On Tuesday, former White House communication aide Cliff Sims explained to CNN's Anderson Cooper that he is suing President Donald Trump because he refuses to be "bullied" and silenced by the president.

Sims, the author of Team of Vipers, which details insights about his short stint in the White House alleges that the president is trying to cut away at his first amendment rights.

Sims' lawyer, Mark Ziad, explained that Trump himself is going after Sims over an apparent breach in a nondisclosure agreement.

"In terms of legally this is an effort being done by the campaign, not by the White House itself. What is the distinction there?" Cooper asked Ziad.

"The distinction would be significant only if that were the actual truth. What they're trying to say is a Cliff in signing the NDA prior to service in the White House, that has essentially in perpetuity, forever applies," Ziad said.

"So if Donald Trump had lost the election and Cliff wrote about it now his time in the campaign, the campaign can certainly go after him. A private entity can go after a private person for the NDA," he explained.

"But that's not what's happen here," Zaid added. "The U.S. Government through the office of the president of the United States has authorized, instructed, approved to have the campaign use their auspices to enforce this NDA to quiet him with respect to his federal service."

"Meaning, this agreement, this arbitration proceeding actually demands that Cliff return government documents that might be in his possession not to the government but to the campaign. I mean, this has the White House all over it."

"But do you know for a fact this is the White House?" Cooper asked.

"From my own sources that I've had and other documents that I'm aware of, it gives every indication and I firmly believe that this is President Trump given instructions to the campaign to take action," Zaid concluded.

Watch below via CNN: