[svd4anything]

Especially a ballon filled with reflective spinning cube, aka Radar reflector.

This theory makes a lot of sense and would imply perhaps an adversary has been spoofing advanced radar systems.

edit: Also reports of underwater disturbances would be consistent with the concept of these being launched by submarines and ... maybe retrieved by them.

[partiallypro]

During these incidents, there were US subs nearby, it's unlikely they wouldn't have picked up foreign subs.

[jonathankoren]

While I agree, it's impossible for us to tell who might be responsible, I wouldn't dismiss foreign subs as easily detected. AIP diesel-electrics are the quietest things out there, and Sweden has one of the best.

https://www.thedrive.com/the-war-zone/21662/swedens-notoriou...