But what if it's a single unit (no warhead) which only works via kinetic contact, then perhaps not a vehicle.
Trust me, if there weren't any laws, people would be shooting down airplanes above their farms, or at the very least, writing a lot of angry letters to the FAA. The laws that we have right now allowing the freedom of air travel were hard-won and unpopular among those affected.
Therefore, the park in this exercise would mostly like try and shoot down the International Space Station, or else risk the reputation of not being strict against surfers carrying surfboards. It's exactly the same thing.
So where do you draw the line?
Similarly a subway train passing underneath the park is not "in" the park, nor are vehicles that are at the antipode of the park on the polar opposite side of the Earth.