Lets say that one day--tomorrow--a space craft from a distant planet that no scientist had ever seen, theorized to be there, much less discovered... crash lands into a piece of government owned land--the US Government that is. Nobody is hurt; there is no damage except to leave a nasty gash on the ground.
The craft and the occupants are threatening in no way, shape or form. They have no offensive or defensive weaponry at all.
All they need are brown leaves that have fallen to the ground to power their spacecraft to leave immediately and there are tons of leaves all around.
How would you play it?