He was instrumental in the Israeli settlement in disputed DMZ territories with Syria, serving as one of David Ben-Gurion's favorite diplomats.

Some time after the Fall of Harbin to the Imperial Japanese Army, Tekoah's family moved to Shanghai for financial purposes.

During his work in the Israeli Ministry of Foreign Affairs, Tekoah was appointed to several positions: He was the President of the Ben-Gurion University of the Negev from 1975 to 1981, following Moshe Prywes and succeeded by Shlomo Gazit.

[2] Historian Avi Shlaim stated that he "could always be relied on [by Israel and the IDF] to produce legal arguments to justify even the most outrageous Israeli actions," and that "in his view the basic function of Israeli diplomacy was to service the country's security needs.

Tekoah spoke fluent Hebrew, English, Russian, French, Portuguese, and Chinese.