On Monday, the Swedish Armed Forces and military units from Denmark, Estonia, Finland, France, Lithuania, Norway and the USA began the Aurora 17 exercise.
The military exercise will be conducted in the air, on land and at sea with units from all over Sweden. Areas covered by the exercise are the Stockholm-Lake Mälaren region, on and around Gotland, and Gothenburg.
Later this week, Russia and its neighbor Belarus will hold joint military exercises Zapad-2017 on Thursday. Those exercises have raised concerns about the potential for accidents, such as planes colliding mid-air, over the Baltic Sea, Swedish Radio reports.
"With two major exercises at the same time, there is always a risk for incidents. The Baltic Sea area will be filled with military activity more than usual for a very long time," says former Swedish army officer and Russian military expert Jörgen Elfving.
The war games have also raised fears of a more aggressive Russia that seeks to show off its military might in the Baltics.
The Aurora 17 drill starts Monday and ends September 29.