Aurora 17 was a military exercise that took place in Sweden during a three-week period, from 11 through 29 September 2017. Its main focus was the defence of Gotland. It was Sweden’s biggest military exercise in 23 years and involved troops from the United States and some other NATO countries. Major general Bengt Andersson served as its exercise director. Events and opinions. Around 21,150 total personnel from all branches of the Swedish Armed Forces, as well as troops from foreign nations participated. One fourth of them consisted of Home Guardsmen.
https://en.wikipedia.org/wiki/Aurora_17