If you don't want your drone to be shot down, keep it over your own property. Any drone that isn't over property you own or rent, at a minimum, is fair game.
This doesn't change just because you are a government.
In fact, since governments can't legitimately own anything, government drones are always fair game. I might give the US government license to fly its drones over the Pentagon, White House, or Capitol building, but nowhere else. No, they don't own those properties either, but I'm willing to compromise that much. At least until they are a threat to adjacent property owners, anyway.
If your drone is over someone else's property, it is trespassing and they have the right to shoot it down. They aren't required to... if you are on friendly terms with them maybe they won't.
If your drone is over "international waters", it's not over your property and shooting it down is a legitimate action. Especially if it is a government military drone. This is because drones "owned" by governments are weapons of war, and their presence is a credible threat to archate.
Keep your drones at home and you won't have to get whiney or become a puffed-up bully when someone shoots one down.