In a message to employees of the Federal Bureau of Investigation (FBI), Director Christopher Wray has said that "Talk is cheap. The work you do is what will endure."
Wray's words followed the public release of a four-page memo which was crafted by Republicans on the House Intelligence Committee, and commissioned by Devin Nunes, the panel's Republican chairman.
"Talk is cheap. The work you do is what will endure. Remember, keep calm and tackle hard," the Huffington Post quoted a letter written by Wray to FBI employees, as saying.
"The American people read the papers, and they hear lots of talk on cable TV and social media. But they see and experience the actual work you do ? keeping communities safe and our nation secure ... and that will always matter more," Wray added.
Wray said the bureau does difficult work "even when it's not easy." But agents do it because they "believe in what it stands for and in what this institution means to people."
U.S. President Donald Trump on Friday announced that he approved the release of the memo, calling its revelations disgraceful.
"I think it's a disgrace," Trump said. "A lot of people should be ashamed of themselves," he added.
The FBI has voiced "grave concerns" about the release of the memo.
The White House made no redactions to the document, despite reported requests from law enforcement officials.
The document has set up a standoff with Trump against both the FBI and Department of Justice.