Sounds like a cluster of balloons with directional radar reflectors on it? So what you're seeing is not a single rapidly moving source, but multiple stationary point sources each being detected intermittently?
However, when you make those assumptions, that opens up a can of worms for other possible explanations. Assuming there was sensor system malfunction, the incident could also be explained though a flock of helicopters flying around. Or it could have been several NSA spy planes flying around. I've seen both those explanations put forth as an explanation for what happened in Belgium.
I don't believe it's possible to disprove either your balloon hypothesis nor the helicopter hypothesis. There's just not enough evidence to make any convincing explanation.
How is it that the systems from various departments of the government. Each of which are totally independent of each other, suddenly all malfunction at once at the same time, and the event happens, and then again the systems get back to functioning perfectly fine?