The “Zapad” exercises also come as Russian forces grind across the sprawling front line in Ukraine and escalate aerial attacks on Ukrainian cities.

Nato’s eastern flank members that border Belarus - Poland, Lithuania and Latvia - are on high alert over the drills, which Belarus says will be held near Borisov, a town east of the capital Minsk.

All three countries have ramped up security ahead of the exercises, with Poland ordering the complete closure of its border with Belarus for their duration.

“The joint strategic manoeuvres of the Russian and Belarusian armies … have started,” Russia’s defence ministry said in a statement.