Zas quickly rose in the military hierarchy, serving in various positions such as head of the Main Operational Department of the General Staff of the Armed Forces of Belarus.

[1] In December 2018 Lieutenant-General Zas was made a candidate for the post of Secretary General of the Collective Security Treaty Organization, succeeding Colonel-General Yuri Khachaturov from Armenia.

[6] It was under his watch that the CSTO deployed active duty troops for the first time in its 20-year history in January 2022, to quell an incipient rebellion in Kazakhstan.

[7] This commitment of peacekeeping forces was mentioned by Zas in his Statement by the CSTO Secretary General to the UN Security Council on 16 February.

"Hypothetically you can imagine it (such a deployment) if there were goodwill from Ukraine – it is after all their territory – if there was a UN Security Council mandate, and if it was needed and such a decision was supported by all our governments."