By Raphael Satter

WASHINGTON, April 25 (Reuters) - U.S. President Donald Trump's purges and apparent acts of retribution aimed at top cyber officials put the nation's digital defenses at risk, the former head of the Cybersecurity and Infrastructure Security Agency (CISA) said in a post on Friday.

Trump's recent moves to fire the two top National Security Agency $(NSA)$ officials and order an investigation into the former head of CISA, Christopher Krebs, were part of a larger movement "that risks hollowing out - and worse, politicizing - the U.S. federal cyber ecosystem when we can least afford it," said Jen Easterly, who succeeded Krebs at CISA.

In a post on LinkedIn, Easterly said that the entire cybersecurity community, including America's foreign partners, were being affected by the turmoil.

"As experienced leaders exit and key roles remain vacant, our nation's cyber defenses are at risk of being dangerously degraded," she said.

CISA and NSA didn't immediately return a message seeking comment.

Trump's abrupt firing of Gen. Timothy Haugh, who led the NSA and Cyber Command, and his deputy Wendy Noble, combined with his announcement of an investigation into Krebs and restrictions on Krebs' then-employer, SentinelOne S.N, have shocked the industry. Neither move was fully explained, but they appear to fit within a larger pattern of Trump using the machinery of state power to punish anyone perceived as disloyal to him personally.

Cybersecurity companies have gone quiet on the matter. None of the 33 major cyber firms approached by Reuters offered comment when asked about Krebs or SentinelOne.

Easterly wrote that the silence from industry leadership needed to end.

"If we allow the quiet dismissal of dedicated public servants in our community to pass without comment - we're not defending national security; we're compromising it."

(Reporting by Raphael Satter; Editing by Hugh Lawson)

((Raphael.Satter@thomsonreuters.com;))