A top official in the National Security Staff at the White House was fired after being caught as the mystery tweeter who had been revealing internal Obama administration information for over two years.
Jofi Joseph, a director in the non-proliferation section of the NSS, was surreptitiously tweeting under the moniker @natsecwonk, a Twitter feed famous in Washington policy circles since it began in February 2011. The feed was shut down last week.
Two administration officials confirmed that the mystery tweeter was 40-year-old Joseph, who had earlier worked at the State Department and on Capitol Hill for Senators Bob Casey and Joe Biden, now the Vice-President.
Until recently, he was part of the Obama administration's team working on negotiations with Iran, The Daily Beast reported.
The Twitter account often criticised Obama administration policies. It openly criticised the policies of his White House bosses and often insulted their intellect and appearance.
Joseph apologised for the tweets and the embarrassment he caused to the administration. "It has been a privilege to serve in this administration and I deeply regret violating the trust and confidence placed in me," he told Politico portal.
"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 apologise to everyone I insulted."
In the course of their investigations, officials suspected that Joseph was responsible for a second anonymous Twitter account "@dchobbyist", which included racier tweets about sexual encounters, escort services and the inner workings of the State Department.
Joseph was asked to leave the White House executive complex after a probe that included an investigation into his travel and shopping patterns, Politico reported.
At different times, Joseph insulted or criticised 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 others.
"I'm a fan of Obama, but his continuing reliance and dependence upon a vacuous cipher like Valerie Jarrett concerns me," he once tweeted.
"Was Huma Abedin wearing beer goggles the night she met Anthony Wiener? Almost as bad a pairing as Samantha Powers and Cass Sunstein ....," he tweeted on another occasion.
A White House spokesman confirmed that Joseph no longer works there but declined further comment.