Between 75,000 and 90,000 Russian and Belarusian troops have taken part in ZAPAD 21.
The military exercise showcases the nations' military might through a number of drills.
Mark Galeotti, Senior Associate Fellow at Royal United Services Institute (RUSI), told Forces News the exercise is an opportunity for Russia and Belarus to "war game" any potential threats.
"But of course, there is also a political dimension, always," he said. "It's about showing that Russia is precisely a formidable military power and also about warning off the West."
He went on: "The ZAPAD exercises always begin with an initial phase which is predicated on the idea that hostile powers, NATO in all but name, is stirring up local protests, sending in special forces in support of them, and this is what actually triggers the whole conflict.
"So, particularly in the context of the current risings in Belarus, it's also a way of saying to the West: 'Don't try anything."