Couple of interesting twitter threads on this from Tyler (The Drive). He suggests this has been coming/happening for some time. https://twitter.com/aviation_intel/status/162414986417840128... Also that we are seeing a lot more now because we have turned down/off the filters on the radars. Which means also we can expect a lot more false positives. https://twitter.com/aviation_intel/status/162461466198661120...
> Which means also we can expect a lot more false positives. Perhaps we can, but clearly we can expect to find actual UAVs corresponding to these radar signals. If these UAVs that have been shot down were domestic research balloons or some other aircraft exempt from FAA regulation, then we can expect a party to come forward and publicly acknowledge ownership/control of the UAV. However, based on the descriptions of t…
Keep in mind that not only US or Canada launches weather balloons. These things are well capable of flying huge distances, including across the oceans. There has been one launched by amateur radio operators a few years ago that has circumnavigated the globe - and that's not at all a rare feat.
See e.g.:
https://qrp-labs.com/circumnavigators.html
So no need to go all conspirationalist about "unmanned drones operated by foreign governments" just yet. Especially given the distances and altitudes these things were found flying at - a heavier than air device would need a ton of fuel and energy to fly that high and that far, so a "drone" that at the same time doesn't look like an aircraft is rather unlikely.