LogFAQs > #971322933

It is between 60,000 and 66,000 feet up and pretty big, you can fit an entire football stadium inside one.
We know that large balloons are hard to shoot down from previous experience. In 1998 a rogue Canadian weather balloon drifted towards Russian airspace. Fighter jets from Canada, Norway and Sweden attempted to bring it down without success. Two Canadian air force CF-18 fighters hit the balloon with more than 1,000 rounds of 20mm cannon fire off the coast of Newfoundland, riddling it with holes. This was not enough to let a significant amount of gas out, and the balloon continued drifting.
A volley of 2.75 rockets was equally ineffective, as the high-explosive rockets simply flew though the balloon without detonating. This may be the Air Forces real concern with intercepting the Chinese balloon: any missile fired at it may be a much greater hazard to civilians below than the balloon itself, which is likely to descend slowly if at all. (The Canadian balloon drifted into Russian territory and is believed to have come down in the Arctic Sea).