 He soon joined Betar and the Irgun and, according to the Irgun website, "took part in reprisals against the Arabs" while still finding time to complete his studies at the Technion as a construction engineer.By 1940, he was a commander of the Betar branch in Haifa, and in early 1944 was transferred to Tel Aviv and appointed member of the General Headquarters by the end of year.In 1947, he represented the Irgun, together with Begin and Shmuel Katz, at a meeting with the UNSCOP.