One of the more surreal sights of the recent Afghan war was tethered balloons (also known as “aerostats”) looming over the bases of international forces. These “persistent threat detection systems” carried a suite of 360-degree cameras providing a constant view - out to 100 miles - of surrounding areas to the US “force-protection” teams within the heavily guarded installations.

The recent four-day saga of a Chinese spy balloon prying into US nuclear secrets serves as a reminder that the oldest technologies are still being developed to achieve military effects today. Balloons have been in use for military service longer than air forces have existed.

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