Jofi Joseph, formerly the director of nuclear nonproliferation issues on the National Security Council staff at the White House, was @NatSecWonk, who took anonymous and often caustic digs at people like former Secretary of State Hillary Rodham Clinton; Ben Rhodes, the N.S.C. spokesman; and Representative Darrell R. Issa, Republican of California and a nemesis of the administration as chairman of the House Oversight and Government Reform Committee.
Administration officials said Mr. Joseph was fired last week after he was unmasked as the Twitter account’s author. The White House official e-mailed to confirm “he no longer works at the White House. Beyond that not going to get into personnel matters.”
The firing was first disclosed by the Web site Daily Beast and its reporter Josh Rogin, who was one of the subjects of Mr. Joseph’s tweets.
“Just a hunch, but I have the sense lots of people would like to punch @joshrogin in the face,” Mr. Joseph wrote on the social-networking site after news reports that Mr. Rogin had been hit by a comedian at a Washington club.
Mr. Joseph was generally respected and popular within the White House, so his secret life took colleagues by surprise. On @NatSecWonk, which has now disappeared, he called himself a “keen observer of the foreign policy and national security scene” who “unapologetically says what everyone else only thinks.”
In that self-described spirit, Mr. Joseph made Mrs. Clinton a particular target. As secretary of state in President Obama’s first term, she “had few policy goals and no wins,” he wrote. And he called Mr. Issa “an ass,” then added, “but he’s on to something here with the @HillaryClinton whitewash of accountability for Benghazi,” referring to the terrorist killings in that Libyan city of four Americans, including the ambassador, last year.
Mr. Joseph apologized in remarks to Politico, the politics Web site.
“What started out as an intended parody account of DC culture developed over time into a series of inappropriate and meanspirited comments,” he told the site. “I bear complete responsibility for this affair and I sincerely apologize to everyone I insulted.”