Sixty former CIA officials released a letter Friday evening condemning President Trump's decision to rescind the security clearance of former CIA Director John Brennan and said the action was comparable to the White House issuing a "political litmus test" to ensure senior government officials agree with the administration.

"All of us believe it is critical to protect classified information from unauthorized disclosure. But we believe equally that former government officials have the right to express their unclassified views on what they see as critical national security issues without fear of being punished for doing so," the letter, signed by analysts, officers, and other personnel, stated.

"Our signatures below do not necessarily mean that we concur with the opinions expressed by former Director Brennan or the way in which he expressed them," it continued. "What they do represent, however, is our firm belief that the country will be weakened if there is a political litmus test applied before seasoned experts are allowed to share their views."

Earlier this week, 12 former CIA officials partnered to denounce Trump's decision to revoke Brennan's ability to get classified information on U.S. national security affairs. Brennan has been a loud critic of Trump's, regularly speaking on cable news networks about his opposition to Trump's leadership style and policies.

At the time, Trump said he did so because of the "rigged" federal investigation into potential collusion between his campaign and Russia during the 2016 election.

[More: John Brennan ready to take legal action to stop Trump from revoking other security clearances]

