[goombastic]

Flight characteristics of some of the observed craft seem to suggest otherwise. Trained observers as well.

[hurrdurr2]

Agreed... a bunch of highly trained fighter pilots mistaking unidentified craft that move in highly erratic manners at high speeds with balloons seem pretty far fetched.

[eitland]

The article clearly says that not all events can be described this way, especially the "tic tac" encounter.

[tomatotomato37]

I don't know, if moderate wind turbulence can cause a multi-ton airliner to bounce the altimeter by 10s of feet, than I can imagine it also moving a ten pound balloon enough to be characterized as performing erratic flight maneuvers

[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.