From a story on politico.com by Lee Hudson headlined “It’s 2023. Why are militaries still using spy balloons?”:

The Pentagon says that a Chinese high-altitude balloon has been soaring above the U.S. this week, adding that it’s carrying surveillance equipment and is violating sovereign airspace.

Spy balloons have been around since the late 1700s, but why are militaries around the world still flying them in 2023?

First, these high-altitude inflatables can conduct surveillance missions for a lower cost than satellites and can carry more payloads than a drone. Modern high-altitude inflatables ride on wind currents and can travel well above commercial air traffic.