The Mossad underwent a shakeup on Sunday after deputy head of the intelligence agency, T., announced his resignation following the government's decision to extend Mossad chief Meir Dagan's term by an eighth year. T., officials said, was an experienced intelligence officer who had served in the Mossad for several decades. He was appointed Dagan's deputy in 2007 after N. - the previous deputy - resigned due to professional differences he had with Dagan. T. was assigned to the IDF Operations Directorate during the Second Lebanon War, and received praise for the close cooperation he instituted between the IDF and the intelligence agency during the war. Another former deputy head of Mossad, Hagai Hadas, who has recently been appointed special envoy to Hamas-Egypt talks on the release of captive IDF soldier Gilad Schalit, left the organization in 2006 after clashes with Dagan. T. started his military career in the IDF General Staff Reconnaissance Unit (Sayeret Matkal) and served in a number of positions in the military before transferring to the Mossad. A senior defense official refused to elaborate on T.'s career in the Mossad on Sunday, but said T. decided to resign after Prime Minister Binyamin Netanyahu refused to promise he would be appointed Dagan's successor in 2010. Netanyahu issued a statement Sunday night about T. saying," the state of Israel is in great debt to him." A successor for Dagan has not been chosen, but defense officials said Sunday that it was possible the next Mossad chief would come from the IDF, and could possibly be one of the generals who will be passed over in the round of appointments slated to be announced in the near future by Chief of General Staff Lt.-Gen. Gabi Ashkenazi.