From pigeon-mounted cameras to dragonfly drones, here's how aerial surveillance has evolved to spy on people over the past 200 years

• A Chinese spy balloon in the US is the latest in a long history of governments spying on each other from the sky.
• Aerial surveillance dates back to the French Revolution to UFO rumors to the Cuban Missile Crisis.
• It's gone from hot air balloons to CIA gadgets to sophisticated live-streaming drones.

Last month, the US government shot down a Chinese spy balloon floating near a South Carolina beach.