I'm not talking just technologically. Are they willing to risk an advanced sub being stuck in Chinese waters? Just like they're not going to risk spies following a convoy of missiles. It's easy to send someone to follow a convoy. Are they willing to risk that? Risk losing people and violating international law is a limit to their capabilities.
Okay, but whether they are willing to risk inserting agents into chinese territory to conduct surveillance missions, or whether they are willing to risk submarines conducting close in surveillance, inherently has to do with the ability for their agents or submarines to be compromised.
In other words, the risk still ultimately comes down to how good the other side is able to detect and prevent their surveillance.
So if they did send that drone, that establishes a limit and not at all close to the hype.
It sets a minimum limit, it does not mean that is the maximum limit. That is to say, what was found is something which falls within the bounds of what they are willing to risk, but the drone tells us nothing about where the bounds actually are.
The people that taunt spies on the ground and Seawolves infiltrating are bragging there is no limit. There is a limit and that alone says they can't do what is claimed at will. And if I recall correctly there was no mention that the underwater drone was found in Chinese territorial waters. If it was found in China's EEZ and international waters, that expands the limit showing the risk they're not willing to gamble contrary to the hype. The more expansive the limit, the less they're capable of doing what they claim whether it's a technological or political limitation.
The people who taunt that spies are on the ground and that seawolves are infiltrating Chinese waters are making sweeping statements with limited evidence and poor logic, there's no reason to stoop down to their level. (By the way, let's remember that there are only three submarines in the Seawolf class, there are many more Virginias and LA class SSNs which conduct similar missions.)
You are absolutely correct in saying that international law should be a deterrent against nations wanting to conduct clandestine intelligence operations against each other, but ultimately whether a nation seeks to break that law depends on their ability to get away with it, and whether they can get away with it or not depends on the other side's ability to detect and prosecute their intelligence operations whether it be HUMINT counter intelligence against an agent on the ground, or a reliable ASW capability against opposing SSNs. (and also of course it depends on how much they need the intelligence as well -- risk vs reward)
The UUV drone says nothing about the extent of USN's SSN surveillance against China, nothing about where they are conducting their missions, nothing about the upper and lower boundaries of accepted risk, and says nothing about how good Chinese ASW is or how good the USN thinks China's ASW is.
All the UUV drone tells us (assuming it is USN), is that the USN is either testing or deploying such technology, and did so in that region of water. It doesn't tell us whether UUV drones are taking over all underwater surveillance of the USN, it doesn't tell us why that drone was there in the first place, it doesn't tell us how big of a risk it is for the USN to conduct SSN underwater surveillance against China.
So statistically speaking, we do not know where the UUV drone sits in the bell curve of the USN's underwater surveillance operations against China. The UUV drone does not tell us where the upper and lower bounds of risk are, it doesn't tell us the majority of kinds of operations which are conducted. It is simply one lone data point that we happened to come across and we don't know if it is representative of a majority of operations or if it is an outlier.
