Eli5 What are the benefits of an “spy balloon” over other methods of aerial surveillance?

Question

It just seems unpractical and low tech

In: 9

Answer 1

They’re extremely practical because they’re extremely low cost. No pilot, no launch, no propulsion system, just set and forget. And, as we’ve seen, the apparent difference between “spy balloon” and “weather balloon” is just semantics and a dash of international diplomacy.

Edit: also balloons can fly at altitudes that make them impervious to most aircraft interventions, and it’s a conundrum for target nations to decide whether to spend a missile on a balloon.