A senior U.S. general in Europe says the U.S. military is keeping a close eye on Moscow's planned military exercises in Russia and Belarus --- exercises that some experts say could involve 100,000 troops.

U.S. Air Force Brigadier General John Healy, who directs U.S. forces' military exercises in Europe, told Reuters on August 3 that Moscow was not being "transparent" in regard to its Zapad 2017 exercises because it is not allowing Western observers.

He said Russian observers attended the recent U.S. and NATO exercises in the Black Sea region, but a similar invitation has not been extended for the Zapad maneuvers set for September.

Russia has said the war games do not require invitations to outside observers, claiming they will involve fewer than 13,000 troops.

Healy said the U.S. military is stepping up its own global exercises in response to a more aggressive Russia and other worldwide threats.

He said the goal was to carry out more challenging exercises that involve forces from all nine U.S. combatant commands -- instead of focusing on specific regions or one military service.

Healy said it was important to conduct war games and training events that reflect the global nature of military threats in the current environment, including cyberwarfare.

He said the U.S. military plans 11 major exercises in the next year that will include air, ground, and naval forces with a range of NATO allies.

Based on reporting by Reuters