Norwegian military

I recently found a picture of my father in a picture that appears to be a military photo. There is a group of 20 "soldiers" in uniform with rifles. This would be about in 1920-1924 ? He came to the United States in 1925. He was born in 1903 Jacob Olaf Farsund (Ludviksen) . He never mentioned to any of my brothers or myself that he was in the army. How would I go about finding out if he was in the "army" or what the picture could represent? Was there a national guard or reserve army in Norway ? Any suggestions would be appreciated. I tried emailing the Norwegian archives and the emails came back "undeliverable". Thanks, Linda Eplin Illinois