Unidentified Object a Weather Balloon?

The balloon-like object an F-16 shot down over the Dimona nuclear reactor yesterday, it's now being reported, may have merely been a weather balloon.

Well, the UFO crowd will have fun with that (I guess "swamp gas" wouldn't be credible in the Negev), but in fact I know from personal experience that, at least in the late 1980s (long enough ago that surely I'm not revealing any vital secrets) Israel had tethered aerostats moored along the Egyptian-Israeli border in the Negev (little mini-blimps on a tether, as low-altitude radar stations to look for smugglers, most likely). If something like that got loose, from their or a neighboring country, I suppose it could have floated.

(Admittedly, I had a surreal conversation with an IDF PR officer back then:

"Do you use the aerostats to look for infiltrators?"
"The what?"
"The balloons."
"What balloons?" (Standing not 100 yards from the nearest, and I'd seen dozens flying along the border).
"That balloon."
"That? Oh, that's just an old weather balloon." I'd recently seen a demonstration in the US of the exact same model by Westinghouse (or maybe GE), and it was quite recent.

On second thought, maybe it was swamp gas.