In 1988, he was appointed Chief of Staff Operations Division of the 7th Army in the Armenian SSR.
At the request of the first Defense Minister of Armenia Vazgen Sargsyan, Zinevich arrived in the Nagorno-Karabagh Republic  in June 1992 and participated in the Nagorno-Karabagh War.

Zinevich was appointed Chief of Staff of the Nagorno-Karabagh Defense Army in 1994, and from May 1997 to August 2000 he served as Deputy Defense Minister. He was personally involved in combat operations and is the creator of operational systems of protection and management of the NKR Defense Army.