Considering that it is the Army, why not BB guns? (small joke)

I think I would consider the long term effect of your actions. I might try to 'kill 'em with kindness', and see if they can't be more careful. Talk to them like you are all in this together. "I totally don't mind you guys playing in my yard, but, now this has happened, and I don't know what to do", and see what they say.

I think if you try to run them out, and they don't go, it is going to be worse on you.