I am not necessarily referring to current events, but you can if you want. Presuppose a balloon is within altitude, and range, of the guns of a warplane made in the 2000's.
Particularly if a military wants to salvage and deconstruct a balloon, then why not use bullets? Leaving something behind to be analyzed! An air-to-air missile is both more expensive and leaves less to be salvaged!
Gail Helt, a former CIA analyst suggests that due to the huge size of the balloon (and almost zero pressure difference between inside and outside) that shooting the balloon full of bullet holes would not bring it down quickly. It would just continue to drift very slowly to lower and lower altitudes (right into commercial aviation traffic) before landing.
From DW News' February 4, 2023 China's spy balloons: What's the geopolitical fallout?
These balloons are so huge that even that kind of - that number of ammunitions - that amount of ammunition set towards it is only going to cause a very very slow leak, and it's not going to come down immediately.
You can't just pop the balloon and it's going to go away.
Presumably the balloon's payload is both of great interest and deserving of some caution. It could have defenses, a self-destruct mechanism, or other undesirable materials so one might not want to simply destroy the payload with a missile, and yet one might not want it landing on the population either.
Thus once it's over the Atlantic an air recovery operation might occur, or now that the balloon is having its "15 minutes of fame" US authorities might even just let it continue and irritate/traumatize other countries for political benefit.
update 1: Then again, maybe not: Video appears to show suspected Chinese spy balloon being shot down reportedly an F-22 fired a single AIM-9 Sidewinder missile and apparently the blast fragmentation pattern from a proximity detonation was enough to rip the balloon wide open and allow the payload to fall into the ocean, and a recovery mission is on its way.
Hat tip to @tedder42's comment:
The Drive suspects the AIM9 was used because it has a laser fuze, not radar
Nice real-time video at Fox 13 Seattle's The moment the Chinese spy balloon was shot down, ordered by President Biden where the balloon is shredded.
Source: New York Times February 5, 2023 China Condemns U.S. Decision to Shoot Down Spy Balloon footage credited to Associated Press
update 2: From BBC's February 8, 2023 When a Canadian weather balloon went rogue:
"We asked the Canadian military if they would consider shooting it down, sending somebody out for target practice," Mr Sommerfeldt said.
A fighter jet had a ceiling of about 60,000 feet, he recalled and "the balloon, of course, was a lot higher than that".
Hoping to save the research, he asked them to shoot upwards and aim for the suspension point, where the release mechanism was for the package of scientific instruments, which were attached to a parachute.
According to news reports from the time, the Canadian CF-18s fired more than 1,000 rounds of ammunition at the balloon - the pilots refrained from using air-to-air missiles.
The volleys of ammo did not work.
"It wasn't enough to shake loose the release mechanism. They probably hit the balloon too. But those small bullet holes and a balloon that size would have almost no effect," Mr Sommerfeldt said.
and
It then drifted back towards Norway before finally landing on Finland's Mariehamn Island after what the Tribune News Service dubbed a "nine-day odyssey".
The instrumentation was sent back to Canada and reused (though there were some bullet holes on the instrument package and its parachute). Mr Sommerfeldt said.
One reason that likely factors into this seemingly odd decision is that Canada tried and failed to shoot down one of their wayward weather balloons using only guns in 1998
A runaway weather balloon floating toward Britain over the North Atlantic is proving a tough target for some of Canada’s top guns.
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.
The CF-18 fighters that caught up with the balloon over Newfoundland and failed to bring it down were equipped with air-to-air missiles, but Lavoie said the pilots refrained from using heavier firepower.
"Citizens would not have appreciated having a missile blowing over their heads,″ he said. "Also, it might be overkill _ spending a couple of hundred thousand dollars on a missile to shoot down a balloon that’s drifting away.″
There's also the fact that nobody was worried about a Canadian balloon drifting over the UK (they used to be the same country). The US would clearly like to know what the Chinese were getting with this balloon. A guided missile with a touchy detonation trigger likely was a better bet.
Some factors that do not seem to be discussed in the other answers:
The Balloon was estimated to be around 60 to 65,000 feet, which is approximately the service ceiling of the F-22, the US fighter with the highest capabilities.
This poses several serious problems for the fighter and its gun.
For an F-22 to maintain flight at that extreme altitude, where the air is very thin, it needs to be supersonic to generate enough lift. When going supersonic, there is a good chance that the plane will actually overtake its own bullets! The bullets start to slow down as soon as they leave the barrel due to the shockwave in front of them, even as the plane is keeping its speed up. It would really be bad if our plane ended up shooting itself down. There is one confirmed case of a plane shooting itself down with its own gun, and I've heard stories of two others (although I cannot find documentation to back it up).
Because the plane would be flying at super-sonic speeds, and the balloon is virtually stationary, it might be extremely difficult to fire accurately at a target as the pilot passes it at extremely high speed.
It is entirely possible that the balloon might've been above, even well above the plane. The plane might not be able to get a nose-up attitude to shoot at the balloon when at the edge of its service-ceiling. This is supported by reporting from TheDrive, indicating the balloon may have been 7,000 ft above the plane.
An F-22 Raptor from the 1st Fighter Wing at Langley Air Force Base fired a single AIM-9X Sidewinder missile that downed the balloon from an altitude of 58,000 feet. The balloon was as high as 65,000 feet.
Shooting a missile covers all these problems:
It's also a good idea to know if a certain munition is capable of locking on to a certain target type and destroying it. This was a valuable experiment in that context, and was funded by the Chinese defense establishment.
As others have mentioned, there is little appreciable pressure between the outside and inside of the balloon meaning it wouldn't "pop" if you poke it full of holes. To give an idea of how many holes we're talking about, time to do a little math.
The chinese balloon is reported to be about 200 feet tall which is gives it a radius of roughly 30 meters assuming its a sphere. Giving a surface area of approximately 11,309 square meters.
The F-22 has 480 rounds of 20 mm ammo, and since its unlikely the bullet will detonate hitting a thing skin fabric of the balloon, we're at best getting 2 holes (entry and exit). The area of each hole will be a circle 314 mm^2 or 0.000314 m^2. 480 * 2 * 0.000314 would mean you'd poke about 0.301 square meters if you get 100% hit rate.
A real world equivalent would be roughly a hole the size of a basketball (24 in wide) in object the size of a football field (200 feet wide). It will leak very very very slowly.
Aside from the (good) answer that, because of lifting gas at the same pressure might only slowly vent through even numerous bullet holes, leading to a potentially slow uncontrolled descent through air traffic lanes, one might be a bit disappointed by a lack of creativity in the response to a drifting balloon.
why not capture it with another balloon?
A rigid airship, like the Zeppelin/Goodyear blimps could be modified for stratospheric flight with external expanding balloons. Pilots would wear SR-71/astronaut type suits. Balloons have flown to over 120,000 feet. This one was sailing along at half that height.
The dirigible could even be remotely controlled. It would only have to latch on to the wayward balloon, release its own lifting gas, and drag it down.
Inspecting and returning it relatively intact to its owners with a mild admonishment of "please be more careful next tine" would seem far more appropriate and diplomatic instead of blasting it out of the sky with a missle.
