The recent flight of Chinese spy balloon over the US highlighted a new kind of overhead snooper. These "pseudo-satellites" fly lower than satellites but higher than most planes and are hard to spot. Camera-equipped reconnaissance planes proved crucial in World Wars I and II, followed by the ever-watchful spy satellites of the Cold War. A Chinese spy balloon after being shot down off the coast of South Carolina on February 4. High-altitude platforms fly above bad weather but have a limited payload, while lower-altitude platforms can carry more sensors but are hampered by weather effects.

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Persons: —, Andrew Payne, Payne, Foxbats, Lockheed Martin, HALE, Christian Otto, Randall Hill, Michael Peck Organizations: Service, Britain's Royal United Services Institute, US Air Force, AIM, North America, Pentagon, US Army, Lockheed, Airbus Zephyr, Airbus, Nations, Defense, Foreign Policy, Twitter, LinkedIn Locations: Soviet, Israel, North, China, America, South Carolina, Forbes