A frequent presence on international television channels, the gravel-voiced Gissin with the bushy black eyebrows cast a formidable figure.
Inner tensions in Israel contribute to a severely complicated period of high alert, ex-IDF spokesman Ran Kohav said.
Hagari was appointed by IDF chief-of-staff Herzi Halevi on January 5, but only took office on Wednesday.
Hagari will be the first IDF spokesperson to emerge from the navy.