A Russian Iskander-K missile is launched 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/AP)
Belarusian military jets fly during military exercises. The Zapad 2017 military drills are held jointly by Russian and Belarusian militaries at several firing ranges in both countries. (Sergei Grits/AP)
Russian troops participate in a military exercise at a training ground near Kaliningrad, 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/AP)
An air-defense missile hits a mock target during military exercises, near a village 125 miles southwest of Minsk, Belarus, on Sept. 19, 2017. (Sergei Grits/AP)
A Russian serviceman attends a military exercise at a training ground near Kaliningrad, Russia, on Sept. 18, 2017. (Russian Defence Ministry Press Service/AP)
A Belarus Army air-defense missile system moves during military exercises, near the Volka village southwest of Minsk, Belarus, on Sept. 19, 2017. (Sergei Grits/AP)
An air-defense missile flies to hit a mock target during the Zapad military exercises on Sept. 19, 2017. (Sergei Grits/AP)
Two Belarusian military helicopters fly during the Zapad military exercises. (Sergei Grits/AP)
The Zapad 2017 military drills held jointly by Russian and Belarusian militaries at several firing ranges in both countries have rattled Russia's neighbors. (Sergei Grits/AP)
An air-defense missile hits a mock target during Zapad 2017 military exercises on Sept. 19, 2017. (Sergei Grits/AP)