OK, plane flying overhead. You shoot it down. Who's going to be held responsible? The airline or the people taking it out of the sky?
Where's the line drawn if the dangerous thing I mentioned before has a practical use? Maybe the balloon is filled with a mix that is toxic to something (crop, livestock, etc). Or there's a component of the payload that is dangerous when hit by a missile or making contact with the ground?
I'm guessing China sees this all as low risk research and nothing more exciting than that, but just trying to imagine what else might be going on, or come next. (I'm not anywhere near either China or the US.)
There may be airlines with slogans like "come fly the friendly skies", but entering controlled airspace without a flight plan or 2 way comms with ATC is anything but friendly. You can try it yourself! Rent a C172 and do some sightseeing in Washington DC. When you get shot down, they will blame you.
One difficulty might be what counts as flying. If it is a balloon and does not include any maneuvering capability the launching country might try to argue that they just released a balloon over their territory. If the upper atmosphere winds take it somewhere else they might say that an act of God and not their problem.
That might seem absurd, but I believe a lot of countries have made a similar argument for pollutants and waste they dump into the air or water. It took decades for instance to get Canada to stop dumping (literal) shit in waters that end up in Puget Sound [1].
A kind of negative of this arises too, when someone takes something out of the atmosphere or water that passes through their territory and someone downstream had been using that thing.
Generally countries don't really do well when it comes to shared resources like atmospheres and oceans and rivers as far as what happens when one does something involving that resource in their territory that affects it in someone else's territory.
This seems like a bad faith twisting of the original question and response.
The original question was about a balloon filled with a dangerous substance, not civilian air traffic.
Civilian air traffic is regulated by the Chicago convention, and shooting it down would be undoubtedly be the responsibility of the nation shooting it down.
The difference is largely one of consent. Nations have the right to control what happens in their air space. But if they consent to civilian air traffic, then shoot down an aircraft that nation is responsible.
If they consent to a balloon filled with dangerous substances in their air space and then shoot it down, then the nation is responsible.
If they *do not* consent to the balloon filled with dangerous substances and shoot it down, then the originating party is responsible.
The hypothetical was about a balloon filled with a "potentially" dangerous substance. e.g., something that had a plausible reason to be there and was likely to be fine if not shot down with a missile.
But it still comes down to consent. If it’s not there at the consent of the host nation (either specific to that situation or via the Chicago convention), then the host nation has every right to take the object down, and the originating party bears most of the moral burden of the situation.
Now, I’d still want the host nation to act as responsibly as possible (for example, the US not shooting down the original balloon over land due to risks to people on the ground).
I still think the jump from the original moral scenario of “no human on board balloon with a potentially plausible argument for being there” to a “passenger aircraft full of people, clearly operating under the Chicago convention” is… quite the leap and really not fairly representative of the original question, and therefore quite unfair to hold to the people who answered the first scenario.
It feels like asking “who’s responsible if bomb disposal techs blow up abandoned luggage”, and then turning around and asking people who respond “Oh?! So what if those bomb disposal techs blow up a bus filled with people??” It’s just not close to the same scenario, to the point of feeling almost like bad faith.
Aside from the fact that the person releasing the baloon might not be a signatory and thus bound by the convention...
"Article 5: The aircraft of states, other than scheduled international air services, have the right to make flights across state's territories and to make stops without obtaining prior permission."
Seems like you don't need permission for a flyover using a baloon because it's not a scheduled international service...
Article 8 clearly distinguishes a balloon from a civilian passenger aircraft.
“No aircraft capable of being flown without a pilot shall be flown without a pilot over the territory of a contracting State without special authorization by that State and in accordance with the terms of such authorization. Each contracting State undertakes to insure that the flight of such aircraft without a pilot in regions open to civil aircraft shall be so controlled as to obviate danger to civil aircraft.”
Separately, Article 3 rules out a state from playing “I’m not touching you” games with a balloon:
“No state aircraft of a contracting State shall fly over the territory of another State or land thereon without authorization by special agreement or otherwise, and in accordance w ~ t hthe terms thereof.”
