A senior White House official has been fired after being unmasked as the acidic voice behind a Twitter account known for its insults of public figures at the White House and on Capitol Hill. Jofi Joseph was director of nuclear non-proliferation on the White House National Security Council staff, but for more than two years sent hundreds of anonymous and abrasive tweets using the handle @NatSecWonk. Something gave him away and he was caught and fired.

Joseph described himself as a "keen observer of the foreign policy and national security scene" who "unapologetically says what everyone else only thinks." @NatSecWonk was popular and Joseph speculated anonymously about the political motives and career moves of administration officials he worked with. Named and shamed were Ben Rhodes, President Barack Obama's spokesman on national security issues. This month, Joseph tweeted that Hillary Clinton, the former secretary of state, "had few policy goals and no wins" in the Middle East.

Joseph was a fierce backer of Republican Representative Darrell Issa, who blamed Clinton for administration actions after last year's attack on the US diplomatic post in Benghazi, Libya.

"Look, Issa is an ass, but he's on to something here with the @HillaryClinton whitewash of accountability for Benghazi," he tweeted.

Joseph admitted that what started out as an intended parody account of DC culture developed over time into a series of inappropriate and mean comments.