Russian President Vladimir Putin, center, walks with defense officials to attend a military exercise at a training ground at the Luzhsky Range, near St. Petersburg, Russia, on Sept. 18, 2017. (Sputnik/Kremlin Pool via AP)
Russia and Belarus began major war games Sept. 14, 2017, an operation involving thousands of troops, tanks and aircraft on NATO's eastern edge practicing how to hunt down and destroy armed spies, among other maneuvers. (Vayar Military Agency via AP)
A Belarusian Army air-defense missile system fires on a position during a military exercise at a training ground at an undisclosed location in Belarus. (Vayar Military Agency via AP)
Russian military helicopters fly during a military exercise at a training ground at the Luzhsky Range, near St. Petersburg, Russia, on Sept. 18, 2017. The Zapad 2017 maneuvers have caused concern among some NATO members neighboring Russia, who have criticized a lack of transparency about the exercises and questioned Moscow's real intentions. (Russian Defence Ministry Press Service via AP)
Russian President Vladimir Putin, center, Defence Minister Sergei Shoigu, left, and Chief of the General Staff of the Russian Armed Forces Valery Gerasimov, second from right, watch a military exercise at a training ground at the Luzhsky Range, near St. Petersburg, Russia, on Sept. 18, 2017. (Mikhail Klimentyev/Sputnik/Kremlin Pool via AP)
A Russian tank rolls during a military exercise at a training ground at the Luzhsky Range, near St. Petersburg, Russia, on Sept. 18, 2017. (Russian Defence Ministry Press Service via AP)
A soldier with Belarus' Army prepares to fire a portable air-defense missile during a military exercise at a training ground at an undisclosed location in Belarus.. (Vayar Military Agency via AP)