The mostly likely culprits are state actors or 'deniable' private agents working for state actors but that there is a desire to ramp down the rhetoric and draw a line under the spat which after all in the world of spying everyone does anyway.
To say the least no, not really, they are not the most likely, not for the smaller objects.
The Chinese have fessed up to the first (big) balloon, though not what it was doing. As for the smaller objects it is worth being aware that some schools, some hobby interest groups and even individuals have been having genuine fun and games flying balloons to high altitude..it's relatively easy to do...couple of it being done legitimately here:
www.facebook.com/watch/?v=1306422636052488
All fine if done in a approved manner ( there are rules on payload size and if and who needs to be notified). However not so fine if it's not done in the approved manner.
@RecoIIectionsMayVary
A million dollars to down a privately owned object? And that is all A OK?
Yep...OK in my book in certain circumstances...
Send something reasonably sizeable but hard to detect up to linger, drifting around, in what is known as controlled airspace at civil aviation cruising altitudes (which the smaller objects were) without notifying anyone and I'd say you're vulnerable to it all ending with a roughly 400k dollar solution.