Were any american U2 spy planes ever shot down? How is a novel weather balloon different from a spy balloon, before you shoot it down? Is shooting at unmanned

Were any american U2 spy planes ever shot down? How is a novel weather balloon different from a spy balloon, before you shoot it down? Is shooting at unmanned aircraft legal in international law? Is sending balloons over other states illegal? Media in germany as usual did nothing to explain anything about the actual facts of what anything means. They just copy and paste the official DPA news and let people without a clue write comments about that, but no actual expert is ever shown in 8 o'clock news for any crisis that takes less than a week.