The Irgun (Hebrew: ארגון), officially the National Military Organization in the Land of Israel, often abbreviated as Etzel (אצ״ל) or IZL, was a Zionist paramilitary organization that operated in Mandatory Palestine between 1931 and 1948. It was an offshoot of the older and larger Jewish paramilitary organization Haganah. The Irgun policy was based on Revisionist Zionism, founded by Ze'ev Jabotinsky. Two of the most infamous operations for which the Irgun were known; the bombing of the British administrative headquarters for Mandatory Palestine in Jerusalem on 22 July 1946 and the Deir Yassin massacre, carried out with Lehi on 9 April 1948. The organization committed acts of terrorism1 against Palestinian Arabs, as well as against the British authorities, who were regarded as illegal occupiers. In particular the Irgun was described as a terrorist organization by the United Nations, British, and United States governments; in media such as The New York Times newspaper; as well as by the Anglo-American Committee of Inquiry, the 1946 Zionist Congress and the Jewish Agency. Hannah Arendt and Albert Einstein, in a letter to The New York Times in 1948, compared Irgun and its successor Herut party to "Nazi and Fascist parties" and described it as a "terrorist, right wing, chauvinist organization". Following the establishment of the State of Israel during the 1948 Palestine war, the Irgun began to be absorbed into the newly created Israel Defense Forces. Conflict between the Irgun and the IDF escalated into the 1948 Altalena Affair, and the Irgun formally disbanded on 12 January 1949. The Irgun was a political predecessor to Israel's right-wing Herut ("Freedom") party, which led to today's Likud party. Likud has led or been part of most Israeli governments since 1977.