All sides use some of the captured spies for exchanges, it's good business. And I'm sure all of them also kill some to send a message, also good business sometimes (in this case 18-20 killed or imprisoned). My point wasn't to single out one agency - FBI, CIA, etc. Is your honest belief that no foreign spies were executed on US soil, or no spy networks were dismantled like this?
"Combatants" (in quotes because the meaning tended to change over time) that take no issues with killing (collateral victims included), torturing, holding people for decades with no due process, or even something as plain and legal as the death penalty for crimes committed by their own citizens, etc. will draw the line at executing a foreign spy that ostensibly deserves it according to most countries' laws and rules of engagement? Why would spies be treated any better than any enemy or even the citizens?
There's no point in singling out one country for something like this unless you're specifically looking to deceive yourself straight up the moral high ground. In this "business" expect things that are lowest of the low on any moral scale. From all sides.
China has a whole gulag archipelago for disappearing and executing dissidents and undesirables. The US doesn't have the infrastructure. The CIA had to spin up a whole set of foreign black sites for its rendition/torture program.
I could see Hoover's FBI doing something like this, but it would probably have come out by now if they had.
Killing your own citizens who spy for foreign countries to send a message doesn't work that well unless you're willing to let it get out that you did it. If nobody knows, then it's not a disincentive! And your adversaries will just recruit more- after all, they're not the ones running the risk, it's your citizens, who don't even know about your new targeted murder program. Quietly disposing of the Rosenbergs instead of putting them on trial might have been easier, but unlike in authoritarian regimes the US wouldn't be able to do anything but keep it a deep dark secret, and the propaganda value and deterrent effect would be wasted.
Killing an entire ring of foreign spies who could be swapped is also stupid, since it means your spies won't be held and maybe swapped, they'll be killed.
Have foreign spies ended up dead on American soil due to US government action, sure maybe, but the FBI or whoever deciding to round up and shoot everyone in a spy ring, nah.
That's the whole "game", isn't it? Police catching criminals or soldiers killing soldiers, you can't say "why bother, there will just be more". And they don't have to be "your own citizens", plenty of Chinese nationals (or naturalized) were caught spying in the US. Why do you think sending embassy staff home would ever be considered retaliation? They are the real control center for intelligence efforts and if you can disrupt such a network even temporarily it's a net win.
> The US doesn't have the infrastructure
Not sure if you're being serious about this. A country that manages to maintain a global military presence including permanent bases, anti-missile shields, ability to execute drone strikes, and ability to kidnap suspects [0] and detain them at black sites [1] spread all over the world doesn't have the infrastructure to what? Identify a spy in their own backyard and "eliminate" them?
> the FBI or whoever deciding to round up and shoot everyone in a spy ring, nah.
Of course, compromising a whole network involves some massive failures so it might be a once in a generation thing. So I'm guessing they just have to deal with spies one by one, as they're caught and according to the needs, instead of "rounding up and shooting everyone". And in the case of the spy ring compromised in China you'll notice that all sources mention it as "18-20 killed or imprisoned". Pretty sure we will never find out how many of each. Quite possibly the ones that were not executed will be traded.
I'm sorry to say it but all this sounds willfully ignorant. You don't become and remain a superpower by playing fair and being soft, it can be expected that all of them fight fire with a bigger fire. The bottom line is that singling out China as the only ones with blood on their hands is terribly idealistic. And unrealistic.
"Combatants" (in quotes because the meaning tended to change over time) that take no issues with killing (collateral victims included), torturing, holding people for decades with no due process, or even something as plain and legal as the death penalty for crimes committed by their own citizens, etc. will draw the line at executing a foreign spy that ostensibly deserves it according to most countries' laws and rules of engagement? Why would spies be treated any better than any enemy or even the citizens?
There's no point in singling out one country for something like this unless you're specifically looking to deceive yourself straight up the moral high ground. In this "business" expect things that are lowest of the low on any moral scale. From all sides.