Something walking upright in Fairbanks County, Alaska

I was part of a group of about a dozen Army personnel training in the area. It was summer on a warm clear day. We were above treeline and had been camped there for several days. I was looking across the nearest valley when I spotted movement. It was on the base of a steep mountainside in bare, rocky terrain, with snowfields descending down the small gullies on the hillside. It was moving up the valley about a half mile away. When it crossed the snow, you could plainly see that it was not a bear. It walked upright with long strides and arms swinging and moved fast across the white snow. It was dark in color like a bear. I have seen bears many times since in the same type of terrain and they do not move like this did. It was too big and fast to be a human. Bears can and do walk upright, usually for short instances when they need to see or smell something and need the height. They don't travel in this manner and not in difficult terrain. I pointed it out to the other guys and we watched it until you could no longer see it. When it was out of the snow it was hard to see against the rocks. We wanted to go look at the tracks but everyone was scared to go down there. We had to sleep there that night and nobody would go outside after dark. The next day we got out and never went back. Twenty years later, I still would not go up there even with a group and with guns. The only thing I have seen that looked like this is the descriptions of bigfoot.