“Joyce is three months past his detail of a year and is deciding to return to NSA,” the official said.

His departure follows that of his boss, Tom Bossert, who oversaw Joyce’s work on cyber security and was pushed out of the administration last week.

Another senior U.S. official said Joyce was leaving the White House of his own volition and not being forced out by President Donald Trump’s new national security adviser, John Bolton, or other personnel. The White House has seen a raft of departures since Bolton began his new role earlier this month.

Joyce is expected to continue in his role for about another 30 days, DHS Secretary Kirstjen Nielsen told reporters during a media roundtable at the RSA cyber security conference in San Francisco.

Nielsen said Bolton will select Joyce’s replacement, calling his departure a “natural inflection point when you have a new national security adviser.”

Joyce was well respected by cyber security experts and widely credited with steering the Trump administration toward trying to impose harsher penalties on foreign adversaries in response to cyber attacks.

The announcement of his departure came just hours after he and briefed reporters on a global cyber attack targeting routers and other networking equipment. They blamed Russian government-backed hackers for the campaign against government agencies, businesses and critical infrastructure operators.

Joyce was scheduled to speak at the RSA conference this week but cancelled, prompting speculation that he would be the latest official to leave the White House.

“It’s a huge loss for the country,” said Curtis Dukes, former head of cyber defense at the NSA who worked with Joyce. “He was very effective in that role.”

Dukes, now vice president at the Center for Internet Security, said Joyce was an asset for all federal agencies and was instrumental in revamping the way the U.S. government decided whether to disclose or exploit cyber vulnerabilities discovered by spy agencies.

Robert Lee, a former U.S. intelligence officer and president of the cyber firm Dragos, said Joyce was technically competent and that many of the previous White House cyber coordinators had backgrounds ill-suited for the job.

“He’ll be missed in the position but hopefully set a standard that future appointments to the position will follow,” Lee said.

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