[citation needed] In 2011, Tarnavskyi was appointed as a Commander of the 17th Separate Tank Brigade and led the combat unit through 2015.

[3] In May 2012, Tarnavskyi attended the consecration of the UOC (MP) church, which was located on the territory of the 17th Separerate Tank Brigade.

[8] During this tenure, Tarnavskyi was involved in the Ukrainian breakthrough of Russian defensive lines in the Russian-occupied Zaporizhzhia Oblast,[9] which in turn resulted in the liberation of Robotyne.

[10] Tarnavskyi was later appointed as the Commander of the Avdiivka front, a position he would hold until the city was captured by Russian forces in February 2024.

Due to recent advances of Russian forces towards Pokrovsk, Ukrainian commander Colonel-General Oleksandr Syrskyi personally replaced Lutsenko.