After experiencing the horrors of war, highlighted in the film by a tormenting sequence of Russian roulette forced by Vietnamese combatants, their lives and seemingly unbreakable bonds are shattered forever.

Source: https://collider.com/deer-hunter-michael-cimino-war-movie/

"It's too frequent, it's happening more, it's like Russian roulette with the cars, we don't know whose car is next.

Source: https://abc7.com/long-beach-arson-cars-set-on-fire/13740360/

They are forced to play a game of Russian roulette with live ammunition, and their vicious enemy enjoys terrifying them.

Source: https://www.slashfilm.com/1211016/director-michael-cimino-didnt-want-the-deer-hunter-to-feel-like-a-political-statement-about-vietnam/