Why we're suddenly spotting spy balloons?

An article in Scientific American on Chinese spy balloons interviews Carla Martinez Machain. “At least since 2018, there does seem to seem to be this broad Chinese balloon surveillance program,” says Machain. “Now that the U.S. military and the U.S. government are looking for them, we’re probably more likely to see them.” In addition to listening in on communications, the balloon could have enabled China to monitor the U.S. response to the intrusive object. “It could be a test to see, ‘How able is the U.S. to detect this type of technology, when do they become aware of it, how easy is it for the U.S. to shoot it down?’” Machain says.