Question

Hello Rabbi,
I serve in a rescue battalion in the Home Front Command.
Our role is to rescue people trapped under rubble in the event that a building collapses as a result of a missile strike or the like.
 
We were called up this past Sabbath בעקבות the attack in Iran in order to take up alert duty in the central region, out of concern that Iran might respond with its own missile attack.
 
From our familiarity with the system, the feeling is that we were mobilized more for backup than out of a concrete concern for danger to life. So afterward we began to wonder whether the situation really justified Sabbath desecration.
It should be noted that about a week earlier they had already mobilized a more limited rescue force consisting of a command post staff, commanders, and senior soldiers, and in all the small real incidents that occurred, that was enough to handle the event. In addition, a rescue force from the Fire and Rescue Authority also always joins in, and in a somewhat larger incident another rescue team is called up directly from home. So we are really intended for a very large-scale event!
 
I asked a Haredi rabbi from my neighborhood, and he argued that apparently this is a case of danger to life not present before us. There is doubt whether Iran would attack at all; even if it did, perhaps they would succeed in intercepting all the missiles as in its previous attacks. Even if a missile were to land, the question is whether it would hit a building, and even if it did, the question is whether there would be people there who needed to be rescued. In his opinion this is too remote and unlikely a concern to justify desecrating the Sabbath with a Torah-level prohibition. He gave me an example: an emergency vehicle should be parked facing the exit so it will be ready to leave immediately, but if before the Sabbath it was mistakenly parked the other way around, it is forbidden on the Sabbath to turn the vehicle around, because that is a case of danger not presently before us, even though statistically there will certainly be an incident on the Sabbath that he will need to drive to.
 
I wanted to ask what the Rabbi thinks, both specifically about this case and also in general about the whole issue of saving life. It is not clear to me when something is defined as "not present before us" and when as "present before us."
It does not seem reasonable to me that one would have to wait until a broad attack actually begins for it to count as "present before us," because by that logic, for example, a combat medic would not be allowed to travel on the Sabbath with a force on an operation in Gaza and remain on alert in case someone gets injured, since no one has yet been injured. If the Rabbi could give clear definitions here in his usual thorough way (if possible, really a halakhic article, we would be happy).
 
Thank you