American UFOs: North Korean?

It seems after the huge Chinese spy balloon, America is having to content with smaller devices entering their airspace.

These have been dealt with in a quick manner, being shot down relatively quickly after detection.

Now these later balloons don't appear to have the same sophistication as the earlier, larger balloon, so I just wonder if they are North Korean. Taking advantage of the same Jetstream. 

The North Koreans are mad enough to send devices with dangerous payloads to America. A relatively small balloon could carry a biological weapon, for instance.

These secondary devices don't appear to be large enough to be spies, but are big enough to deliver a payload. 

Just a thought exercise.

And why would the Americans be so keen to shoot this wave down in the frozen North? What intelligence do they have on this new wave of devices?