The White House has fired a National Security Council staffer after an investigation revealed he was behind a Twitter username, @natsecwonk, that had been trolling top-level members of the administration for a long period of time, Politico reports:

Jofi Joseph, 40, was fired from his job on the NSC nuclear non-proliferation team a week ago after a months-long probe into a barrage of tweets that included caustic criticisms of former Secretary of State Hillary Clinton and top NSC officials, especially Ben Rhodes – whom he accused of dodging questions about Benghazi.

“It has been a privilege to serve in this Administration and I deeply regret violating the trust and confidence placed in me,” Joseph told POLITICO in an email.

“What started out as an intended parody account of DC culture developed over time into a series of inappropriate and mean-spirited comments. I bear complete responsibility for this affair and I sincerely apologize to everyone I insulted.”

The Daily Beast adds:

At different times, he insulted or criticized several top White House and State Department officials, including former National Security Advisor Tom Donilon, Deputy National Security Advisor Ben Rhodes, Secretary of State John Kerry, and many many others….

For many in the foreign policy community reacting Tuesday night, the revelation that Joseph was the mystery tweeter @natsecwonk was a shock because Joseph was well known among policy wonks and his wife, Carolyn Leddy, is a well-respected professional staffer on the Republican side of the Senate Foreign Relations Committee.

But inside the administration, there was little sympathy for the man who they feel had betrayed their confidence while taunting them all the while.