Example with Iraq is again irrelevant. It is irrelevant because comparison of China to Iraq is simply invalid.
You spoke of hitting targets within China as if it will be a cakewalk. In reality, China has the land-equivalent of everything you can find within a CVBG, so the task will be as difficult if not more so than raiding your own CVBG with aircraft and cruise missiles. Assets within China are not limited by the sea and have home-field advantage, two things that a CVBG doesn't have.
The comparison is valid because the SOSUS system's layout is similar to how Iraq laid out their fibre optic communications grid. There are hubs and nodes that if targeted, can knock out vast sections of that grid.
And fixed, land based targets are easy to target. They are fixed, and static. Yes, you can try to bury them in heavy duty bunkers, but the US has demonstrated bunker busting capabilities. The Iraqi's buried their command bunkers deep into the sand and built them with 6 metres of reinforced concrete. We penetrated such bunkers with ease in Desert Storm.
You can try to defend them; the Americans have the B-2 which is stealthy, and can slip past such defences, especially at night, and in poor conditions.
Trawling activities do damage undersea cables, but these can be repaired. Furthermore, modern undersea cables can be buried, thus mitigate against most human induced damage. Expensive is a subjective term, but the US did not find the maintenance of SOSUS to be cost-prohibitive. Towards the end of the Cold War, the US was even using hydrophones that only have "look up" capability, necessitating large number of them to be placed and immense amount of cabling. Again, the US did not find that to be cost-prohibitive either.
A hydrophone network is simply not a house of cards as you made it sounds to be. Your cost argument also holds no water, especially when you provided no comparisons to the cost of other military systems.
I demonstrated that such systems can be systematically damaged easily. The Americans can say, lean on the Japanese, Taiwanese, and South Koreans and other allies to send their trawler fleets around Chinese SOSUS lines and damage them. Or they can send their own ships to do the same. And since such repairs take time, damaging them at a critical time means that repairing the damage in time is not feasible until a conflict ends.
And burying cables is often of no use; trawling activity can leave deep gouges in the seabed, uncovering buried objects.
While you keep on portraying the SOSUS to be useless, the fact that US has operated the network throughout the Cold War says the complete opposite.
It offered increased probability that they could find and track Soviet subs. It does not guarantee 100% detection and tracking.
Wrong! Your list contains nothing more than reconnaissance satellites, radars (that do the samething as HF/DF), and assets that gather signal intelligence. China has all that. Furthermore, China has access to sheer computation power that US didn't have access to back in the days. Signals that were too computational expensive to extract thus being undetectable are no longer the case today. Code-cracking is not an unique ability of the US, and you have no proof that China doesn't operate its own signal monitoring stations on foreign soil.
And exactly how often is "often"? 1/10, 5/10 or 9/10? This paragraph says completely nothing.
Reconnaissance satellites and radars are NOT the same was HF/DF. HF/DF is signals interception. It's about intercepting a radio transmission and triangulating the signal.
In order to allow SOSUS to detect and track Soviet subs heading into the Atlantic, it has to be cued and alerted beforehand as to where to look. We could detect when a Soviet sub receives orders to sail out. We then used our reconnaissance satellites to look at Soviet naval bases to see which subs are preparing to set sail. Once US intelligence was made aware, they passed the information to SOSUS so they had an idea where to look and when, could they attempt to track Soviet subs heading into the Atlantic. We then could send our attack subs to trail Soviet subs as they conducted their patrols.
However, we did loose contact on a number of occasions, or never detected Soviet subs in the first place. For example, the USS Batfish in 1978 was tracking a Yankee class SSBN. Batfish lost contact with the sub during a heavy storm, and until a P-3 assisted the search and the storm subsided, they did not find the sub.
At times, we never detected the submarine in the first place; for example, during the Cuban Missile Crisis, US forces were only able to find 3 out of 4 Foxtrot class submarines in the area. The last one was never found.
