This is a very good take on the topic, and makes a key point: "people expect one blanket and grand explanation for the entire UFO mystery to one day emerge. This is flawed thinking at its core. This issue is clearly one with multiple explanations due to the wide range of events that have occurred under a huge number of circumstances."

There is a very high likelihood that Russia and China have been employing UAS's to gather intel on our training exercises, and they do not have to have cutting edge technology to do so.