At high altitude these sorts of balloons are massively stretched out due to the low atmospheric pressure. A puncture will cause catastrophic failure of the balloon.
> A runaway weather balloon floating toward Britain over the North Atlantic is proving a tough target for some of Canada’s top guns. The helium-filled balloon, a 25-story high unmanned research station used to measure ozone levels over Canada, was launched Monday from Vanscoy, Saskatchewan.
> Jet fighters trying to bring the balloon down fired more than 1,000 rounds into it Thursday, but it remained aloft. The air force hopes the now-leaking balloon will eventually come down.
>``It’s at an altitude and an area where trans-Atlantic flights pass nearby,″
That is around 35k feet. I’m talking about the altitude that the recent Chinese balloon was at, around 60k feet.