Could unidentified objects represent another 'Sputnik moment' in U.S. skies?

The White House says that the three flying objects U.S. fighter jets shot down last weekend were probably not spying on us — they could be benign, for research or commercial purposes. And, they originated on Earth (no aliens to see here.) That got us wondering — who’s finding these things? And why are they suddenly popping up so often, after the U.S. popped a much larger, suspected Chinese surveillance balloon earlier this month?