Russian President Vladimir Putin's spokesman harshly criticized the event on Tuesday, suggesting it actually undermines security in Europe by damaging relations with Moscow.
This exercise "clearly does not contribute to an atmosphere of trust and security in the continent," spokesman Dmitry Peskov said in comments carried by state news agency TASS.
Many of the Western military alliance's member states are participating in the Polish-led exercise, codenamed Anakonda-16. Poland expects 31,000 soldiers to train during the 10-day event, the largest ever conducted by its armed forces.
Dozens of fighter jets and ships are due to take part, along with 3,000 vehicles. The United States is expected to provide the biggest contingent of foreign troops, while non-NATO countries such as Ukraine and Georgia have also been invited.
The show of force comes at a time when relations between Moscow and the West have hit a post-Cold War low due to Russia's annexation of the Ukrainian peninsula of Crimea and its support for separatists in eastern Ukraine.
NATO leaders will consider during their July 8-9 summit in Warsaw whether to deploy battalions to Poland and the Baltic countries - Estonia, Latvia and Lithuania - as part of their response to Russia's actions.
Moscow has repeatedly warned that NATO's eastward expansion threatens its national security.
Deputy Foreign Minister Aleksey Meshkov told the news agency Interfax on Thursday that the military exercise being conducted in Poland and another being held in Lithuania were destabilizing.
He charged that the main aim of the manoeuvres is to "stoke tensions along the Russian border."
Anakonda exercises have taken place in Poland every two years since 2006. Some NATO countries have been keen to portray this year's event as a signal to Russian President Vladimir Putin, but others - notably Germany - would prefer to play down tensions with Moscow.
"In the long run, we just have to understand that Russia is our biggest neighbour," NATO Secretary General Jens Stoltenberg said on Monday evening at a Brussels event held by the Politico media outlet. "We have to relate to Russia and we have to work with Russia."