I am by no means an expert on this but I don't think this is military in my opinion. I have never seen a seam in the middle of the back of a military garment,they are usually one piece of material until you get to the sides where the arms start. Also, the buttons on all of my military jackets do not have the buttons sewn all the way through from the outside to the inside of the jacket. The way all mine are made are the buttons are sewn on before the lining of the jacket is applied.now on your example the buttons could have fallen off at some point and someone stitched them back on going all the way through the liner of the jacket, but who knows.most military garments also have the drawstring to where you can cinch the waist section of the jacket snug around the waist. The draw string on your example seems to only adjust the way the back of the garment fits to the body. I'm sure eventually someone who knows exactly what this is Will chime in