How high-tech spy balloons became so popular for aerial surveillance

Military interest in balloon surveillance had been increasing even before a Chinese-launched balloon wandered across the continental US

By Jeremy Hsu

Surveillance balloons are having a moment – even beyond the recent Chinese spy balloon fiasco.

The US and UK militaries are increasingly funding projects to build high-tech surveillance balloons that operate at nearly 20 kilometres up in the air. And though Chinese officials have said that the balloon at the centre of the recent incident was a weather-monitoring balloon and not a spy balloon, China has also been putting a greater focus on surveillance balloons.

“You can fit a lot more surveillance capacity on a …