Ok so it’s either a massive foreign program or UFOs.
The air defense folks increased the sensitivity of radars and started finding the UFOs. Maybe the UFOs were keeping away from population areas and radars but now were being picked up.
It is strange that the objects aren't stealthed. Which makes sense for balloon payload. But stealth, hovering, car-sized objects should be hard to detect. Maybe aliens don't know about stealth. The other weird thing is that they just hover. For advanced or alien technology, I would expect them to move away or dodge.