There's a book called "Volcano Cowboys" about the USGS and Mt. St. Helens, Pinatubo, and I think Nevado del Ruiz in Columbia, and about their prediction attempts, etc.
They had the easiest time at Pinatubo because it was easy to get the Air Force leadership to understand the science involved, because of their educational background.
I recall from the video that one of the real concerns they had was if their prediction didn't pan out. The locals who evacuated would not the next time and there would be a tremendous loss of life. The volcano blew just at the end of the warning period, just before people would have been going back to their villages.
Probably, the military bases had some impact because if they were moving out, it would cause the locals to think twice. It's been a long time since I've watched it; I'll have to plug it in again. It was so good that a college geology professor friend of mine borrowed it to show his classes.