Future PLAN orbat discussion


AndrewS

Captain
Registered Member
J-20 would not be regularly operating 1500 km away from china, the same way Superhornets would not be operating at over 1000 km from the carriers, most of the time. Sure, occasinally, some J20s may get to perform an operation 1500 km away from China, after refueling. But it wouldn't be patrol, it'd be some escort mission or strike mission. As a rule, though, they'd stick closer to China, as it's very unlikely they have such range. and why are we even talking about J20 range when there's no way for us to know such figures?
I reckon the Chinese Air Force could operate airborne tankers some 300km off the Taiwan coastline, which is only 600km from the Chinese coastline.
Remember there is likely to be a SAG or Carrier Group in the same area.

So establishing a continuous CAP (with J-20/J-15/J-11) at 1000-1500km from the Chinese coastline would be feasible.

Note that 10 years ago, doctrine looked at F-22s operating from Guam to Taiwan.
That is 2800km outbound and would require 2 air refuelings. Then the same again inbound.

So Chinese J-20s operating 1500km from mainland China would be following a similar operating profile
But 1500km is only half the distance that the F-22 was planning on.
Also remember that the J-20 and F-22 are roughly the same size, but by most accounts, the J-20 has more fuel capacity and therefore range.
 

AndrewS

Captain
Registered Member
I disagree, of course.

Tankers can indeed "hide" on the ground. At one point there at position X, the next hour they're on position Y, a few hundred meters away. aerial and space based recon is not at the level where every target over Japan is revisted every half an hour.
Moving a large tanker or bomber a few hundred metres is not going to help.
Guided munitions or cluster munitions are standard, and it only takes 1 bomblet to put an airplane out of service.

There are quite a few RAND/CBSA studies which look at the vulnerability of large aircraft when they are on the ground.
Overall, that favours operations where large aircraft aren't needed.

Plus we are entering an era where satellites do provide near real-time surveillance. See below.

The original plan was to have 16 satellites in orbit until the end of 2019, completing a remote sensing network that will cover the entire globe and will be capable of a three to four hours update in the data provided

From 2020, the plans point to a 60 satellite orbital constellation capable of a 30 minutes update in the data provided.

From 2030 the Jilin constellation will have 138 satellites in orbit, forming an all-day, all-weather, full-spectrum acquisition segment data and a capability of observing any global arbitrary point with a 10 minute revisit capability

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China does have more airbases and strategic depth but we disagree on just how few bases the US/Japan side would have. And lets leave it at that disagreement as it'd be pointless to go further.
Let's say Japan did become a huge militarised camp for the US Air Force, with as many airbases and runways as you suggested.
It doesn't change the analysis and the overall conclusion.

Which is that China will always have a lot more airbases and runways.
And that US/Japan will run out of medium-long range missiles first, whilst China will still have missiles to use against Japanese airbases.
Which means Chinese fighter jets and AWACs could conduct strike and air superiority missions, whilst the opposing airbases are being suppressed.

So again, why should Japan follow the USA in a war against China?
 

AndrewS

Captain
Registered Member
well we seem to agree on general financial inefficiency of carrier use, compared to land airbase use. I really won't go into further details where we disagree as this discussion would never end, if I did that.
Well, a Ford-Class carrier is $13 Bil.
And say you need 2 carriers to keep 1 continuously on station, given maintenance and sailing times.
The current cost of a carrier airwing with 60 aircraft looks like $5-6 Bil.

So that is $26 Bill of aircraft carrier to serve as a platform for just 60 airplanes worth $6 Bil.

That suggests you could buy 2 airbases with 120 airplanes for just $12 Bil.
And still afford a large fleet of tanker aircraft based securely in a rear airbase.

Plus that doesn't factor in the cost of carrier escorts.
Nor how carrier aircraft are lower-performance and more expensive than their land-based counterparts.

So an aircraft carrier looks *grossly* inefficient, if you have the option of using an airbase combined with tankers.

For the current moment, and for the next decade or so, China gets much more by adding land based planes than by adding carriers. Yet one has to start somewhere with the carriers, if by 2040 or whenever China wants to have even an option to go out into the Pacific during a war.
Agreed.

Eventually I expect China to build up a fleet of large carriers, but that won't be for some time.

Remember, China doesn't actually need carriers to control the sea in the Pacific Ocean.
China's core objectives only require sea-denial in the Western Pacific.

They should be able to do this with land-based aircraft and missiles.

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And it looks like they are preparing for a large increase in construction at Huludao Shipyard.

If they were to produce 3 SSNs/SSGNs per year in the next 10 years, then that is 30 additional boats.
That would typically mean 3-4 extra submarines on patrol at any time, and potentially 17 more boats ready to surge.
Most would pass the 1st Island Chain within a day.
In any case, the Chinese Navy and Air Force is confident it can *control* those approaches, because they are so close.

The US only has a total of 6 SSNs typically on patrol at any time and they are the only boats able to keep up with Chinese nuclear submarines.
So a significant number will be able to disappear into the Pacific Ocean.

Large numbers of nuclear submarines would fit with a Western Pacific sea denial strategy.
Plus those nuclear submarines would also be able to operate in the Eastern Pacific and indeed globally.
The submarines could also project power on land with offensive cruise missiles, particularly against soft targets.

At a minimum, the submarines could operate against soft targets such as the *few* resupply ships which are critical to projecting power across the Pacific.
But if there are sufficient numbers of quiet-enough Chinese submarines, they could be tasked with riskier targets.
 

AndrewS

Captain
Registered Member
Guam is not the only rear base. There will be other bases - either newly constructed, or expanded existing runways or commercial runways used. Again, we already talked about this in other threads so i feel silly for repeating myself.

Guam the island has a commercial airport as well. It also has another old airstrip area at the northern tip of the island.
Rota island has an airstrip.
Tinian has an airstrip and another old airstrip area up north.
Saipan has a commercial airport.
Iwo Jima has an airbase.
Ko Jima has an airport.
Palau has an airport. And it's an associated US territory and it would NOT be neutral in a war.
Wake Island has a base. Though granted is sufficiently far away that it'd likely be a stopover base or perhaps a bomber base.
All the above are 2 km or longer runways, with sufficient area to expand them to 3 km, if needed.

Then there are the RyuKyu islands. There's a few dozen runways/airports on those, as I wrote in one of the other threads. On mainland japan there are over a 100 sites (airports or airstrips) with fairly long runways. There's A LOT of place to put various aircraft on. Commercial traffic would take a distant second place when it comes to priority of usage.
All these runways are located on tiny/small islands, with barely any land-area, nor much civilian logistical support.

1st Island Chain
The ones on the Ryukyu Islands (on the 1st Island Chain) are all within 800km of mainland China and really vulnerable.
It's not just about the number of runways. It's also the distance at which they are located at.

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2nd Island Chain
The other islands you've mentioned are mostly in the Marianas like Guam, 3000km from mainland China.
The exceptions being Palau (2400km) and Wake (4800km).

But these aren't rear bases despite what you think.

At a distance of 3000km+, you need a lot of large expensive aircraft like Tankers or Bombers.

A B-21 Bomber is supposed to be $550M
A KC-46 Tanker is around $150M

But these aircraft are impossible to hide.

Just look at the commercial satellite imagery available for these runways and airbases.

Plus a single small cluster bomblet is enough to put an aircraft out of commission.

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In comparison, CASIC is offering a commercial CZ-11 launch for $7.5M, excluding payload/warhead costs.
The CZ-11 is solid-fueled, vehicle launched and supposed to be based on the military DF series.

It can put 1500kg into low-earth orbit, so it can certainly deliver 1500kg to a distance of 3000km for Guam. Or indeed Wake Island or Hawaii.

1500kg is a lot of kinetic rods or ball bearings. And these could be delivered at hypersonic ICBM speeds and/or with a manoeuvring reentry vehicle.

Note that THAAD can't intercept incoming ICBMs. And whilst the SM-3 might be able to intercept, it costs $18M, which means defensive engagements will cost a lot more than the incoming missiles.
 

AndrewS

Captain
Registered Member
SIPRI weapons procurement estimate released.

The vast majority of the estimated $70-$80 billion worth of Chinese munitions sold every year are bought by the different branches of China’s People’s Liberation Army.

This still represents a dramatic shift over the last 10 years as China in the past was a big importer of weapons from Russia and Ukraine.

“They no longer need to rely on other countries for their weapons,” Tian said.

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But we can see that US warships are 2-3x more expensive than their Chinese equivalents, which is being very generous to the US Navy, given that Chinese "equivalents" are larger and better armed. For example.

1. A 10000ton Arleigh Burke Destroyer ($1800M) versus a 13000ton Type-55 Cruiser ($950M)
2. A 3000ton LCS ($800M) versus a 4000ton Type-54A Frigate ($300M)

Note these are the 2 most common types of ships in the US Navy, and should be representative of costs for other ships.

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The US currently has a procurement budget of $147 Bil.
That is roughly 2x the Chinese figure, using nominal exchange rates.

SIPRI also estimate the Chinese military is self-sufficient now, with minimal imports.
This matches with the University of Birmingham paper.

This has a number of implications:
1. It supports the use of the consumer PPP exchange rate, which implies that for every dollar, the overall Chinese military gets twice as much as the USA military.
2. It also implies that the Chinese Navy is "outbuilding" the US Navy in terms of equivalent ships.

Furthermore SIPRI estimate Chinese military spending at 1.9% of GDP, versus the US figure of 3.2%.
So this level of Chinese Navy production can be sustained for some time.

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Yes, there are operations and maintenance costs as well, which account for the majority of Total Lifetime Cost for a naval ship.
But the ongoing costs and initial construction costs use the same labour, equipment and shipyards.
 

Totoro

Captain
VIP Professional
I wanted to move the discussion to another topic so this topic isn't polluted as it's offtopic... but It was brought to my attention any discussions such as these may not be allowed?!? Until I know more, I'll keep the replies here but I am really even more sure that this is all so very offtopic. Yet I don't know where to move it.

I reckon the Chinese Air Force could operate airborne tankers some 300km off the Taiwan coastline, which is only 600km from the Chinese coastline.
Remember there is likely to be a SAG or Carrier Group in the same area.

So establishing a continuous CAP (with J-20/J-15/J-11) at 1000-1500km from the Chinese coastline would be feasible.
Who knows where China could operate its tankers with impunity and for how long. 600 km from chinese coastline personally seems to far away, and too close to various possible bases in Japan. But i'm sure different people will have different ideas about that.

Establishing continuous CAP anywhere, by any air force, especially so far away from a base, 1000+ km is extremely costly. Perhaps a small group of planes could be maintaned on cap, depending on air force size. But realistically CAPs are not the way to control an area. A cap 1250 km away from a base, for example, needs one full refueling and roughly 3 hours of transit time as well as 3 or so hours of patrol time. Over a long time period, meaning weeks or more, a plane participating in such CAP would be able to do one sortie per day. So, for each one of those planes on CAP, there would have to be 8 planes in total available. For 12 planes on CAP, for example, one large tanker would be needed to support them, and 96 combat planes would be needed overall. To maintain a huge CAP of 100 planes, one would need 800 fighters. With 6 hours of flight per day, within a few months the fighters would get worn out enough that they'd need maintanenace that can't possibly be done within the 18 hours remaining between missions. So more fighters would be needed to upkeep such a CAP. Possibly even a 1000, to upkeep those 100 planes. Right now, entire Chinese air forces have roughly 1050-1100 decently ranged and decently modern fighters.

and what could be achieved? Bunch of fighters would be grouped and tied to one single area. Perhaps a circle with several hundred km radius. Leaving still a much bigger area unattended. Leaving Chinese airspace undefended. Leaving bunch of strike opportunity areas without fighter escorts. Basically, such a strategic move would defeat itself and hand the victory to the enemy.

Which is why I believe no side would really attempt to do long term CAPs with many planes far away from a base.


Note that 10 years ago, doctrine looked at F-22s operating from Guam to Taiwan.
That is 2800km outbound and would require 2 air refuelings. Then the same again inbound.

So Chinese J-20s operating 1500km from mainland China would be following a similar operating profile
But 1500km is only half the distance that the F-22 was planning on.
Also remember that the J-20 and F-22 are roughly the same size, but by most accounts, the J-20 has more fuel capacity and therefore range.
I'd personally say J-20 should be able to do 3500 km of ferry range, perhaps even a bit more. That still doesn't mean J20s would be operating far from Chinese shorts regularly. There's not many of them and there are not many tankers available. And certainly only a small portion of tanker capacity could go to J20s. So any J20 going to 1500 km away from Chinese mainland would be an exception, not a rule. With US tanker numbers, their planes could operate farther from their bases on a more regular basis. Though again probably not anywhere close to a near constant basis.

Moving a large tanker or bomber a few hundred metres is not going to help.
Guided munitions or cluster munitions are standard, and it only takes 1 bomblet to put an airplane out of service.

There are quite a few RAND/CBSA studies which look at the vulnerability of large aircraft when they are on the ground.
It takes hundreds or thousands of bomblets detonated to make sure that enough of them hit an aircraft and that enough of those hit areas where they would seriously damage the plane. Desert war had situations where planes regularly flew with dozens of small holes from various shrapnel.

So we disagree. Dispersing planes would definitely help as more munitions would be needed and there's not enough guided and stand off and cluster munitions in Chinese arsenal (or US arsenal, for that matter) to simply destroy most planes on the ground, regardless of the size of those planes.


Plus we are entering an era where satellites do provide near real-time surveillance. See below.
For one area, sure. For multiple, hundreds of targets at the same time, no. Plus there's cloud cover muddying up the picture. Over Tokyo, for example there's cloud cover roughly 50% of the days in the year. Then there's the issue of analyzing all those targets and the subtargets in each area. Getting the data to strike force. The force needs to do a mission plan, brief the pilots. The kill chain may've been brought down to under an hour for select high priority targets where a disproportionate portion of resources are following that target. But in a total war with so many targets, average kill chain time from detection to strike would still be many hours.

Which is that China will always have a lot more airbases and runways.
And that US/Japan will run out of medium-long range missiles first, whilst China will still have missiles to use against Japanese airbases.
Which means Chinese fighter jets and AWACs could conduct strike and air superiority missions, whilst the opposing airbases are being suppressed.

So again, why should Japan follow the USA in a war against China?
China will have many more bases and targets, sure. Which is why US can't really do much to mainland china by military means. But for similar reasons -
enough of targets, distance to targets, number of strike platforms and their range and number of missiles - China too can't really bomb Japanese targets into oblivion either.

Both sides would run out of their "big" missiles very quickly. While perhaps shutting down several dozen of targets for a limited time. It's hard to quantify really. A powerplant
can be shut down with several hits for several weeks in theory. A base with 3 runways would take probably 50+ missiles per day just to keep those runways shut down.

As mentioned before, China lacks range to even reach a sizable part of japan and shut down the airbases there with sufficient number of missiles. I would be repeating myself here so who is interested can check out my previous posts. Once again - would US be able to shut down Chinese airbases? Not by a long shot.

I don't know why would Japan follow US in a war. My whole assumption is that it would. And the whole discussion here started by a claim "IF Chinese military was twice the size of US and Japan's military then Japan would not help the US" I don't know if that'd happen. But given how such numbers ratio is not possible for the next several decades, we are left with the situation today, where Chinese military is far from such a ratio. Without Japan, US can't do much against China. So to make the whole discussion at least a little bit meaningful, I do assume Japan is all-in. As i don't believe there'd be half assed solutions. Limited involvement is very unlikely.


Remember, China doesn't actually need carriers to control the sea in the Pacific Ocean.
China's core objectives only require sea-denial in the Western Pacific.

They should be able to do this with land-based aircraft and missiles.
I do believe China can deny the seas to US/Japan out to the first island chain for unlimited time.
And even deny the islands and seas little farther out (a few hundred km more?) for a limited time, until the entire US war machine
relocates to the area - which should take a few months.

That still means that a large part of the seas between the two island chains would be contested at times and would not be an area where US can freely sail and move in all the time.
 

Totoro

Captain
VIP Professional
And it looks like they are preparing for a large increase in construction at Huludao Shipyard.

If they were to produce 3 SSNs/SSGNs per year in the next 10 years, then that is 30 additional boats.
That would typically mean 3-4 extra submarines on patrol at any time, and potentially 17 more boats ready to surge.
Most would pass the 1st Island Chain within a day.
In any case, the Chinese Navy and Air Force is confident it can *control* those approaches, because they are so close.

The US only has a total of 6 SSNs typically on patrol at any time and they are the only boats able to keep up with Chinese nuclear submarines.
So a significant number will be able to disappear into the Pacific Ocean.
US has 50 something SSNs today. Assuming two thirds are out of maintenance and one third is on deployment, that's some 16 subs. Transit time from US western coast (most would be relocated there, though some would be homeported even closer) is some 18 days, leaving some 72 days of patrol time on station. So roughly 13 subs available in area for combat.

I really don't advise mixing the timelines. Some aspects of the discussion seem to be for today, others 10 years into the future, others still 20 or more years. That's not way to discuss anything. Since predicting future is hard, i'd personally advise to stick to today.

Today China has perhaps 9 SSNs. 6 would be out of maintenance and 3 would be on deployment. Since distance to combat area, if the combat area is 1st to 2nd island Chain area, one could say that almost all 3 subs would be available.

Sure, in 10 years time there MAY be a fleet of 35 SSNs. Just like the US MAY have a fleet of 60 subs. or in 20 years time China MAY have 70 SSNs. And US MAY have 80 subs. But that's even silly to try to predict.

At a minimum, the submarines could operate against soft targets such as the *few* resupply ships which are critical to projecting power across the Pacific.
But if there are sufficient numbers of quiet-enough Chinese submarines, they could be tasked with riskier targets.
The "few" resupply ships is a myth. Back in the cold war, soviets had NO chance to suffocate the transport ships in the atlantic. There were tens of thousands of ships available to western powers, which would in large part be used for the war effort. Similarly, going after various transport ships would be a failed strategy for China. One needs to find a ship, make sure its the right ship and waste its torpedoes on it. And sure, even if it sinks 30 ships, what then? Go back to base? Hope to survive that whole time? And try to do it again, every 10 or so days? (could it even find 30 targets within a week?) US and Japan have less ships than NATO countries had in 1980s but even the 6000 merchant ships they do have would be A LOT.
Going all with subs, after those merchant ships would mean no nuke subs left for combat ops between the two island chains. Again, not a good strategy for China in my opinion.




All these runways are located on tiny/small islands, with barely any land-area, nor much civilian logistical support.


The ones on the Ryukyu Islands (on the 1st Island Chain) are all within 800km of mainland China and really vulnerable.

The other islands you've mentioned are mostly in the Marianas like Guam, 3000km from mainland China.
The exceptions being Palau (2400km) and Wake (4800km).

But these aren't rear bases despite what you think.

At a distance of 3000km+, you need a lot of large expensive aircraft like Tankers or Bombers.
Logistical support is built up. Vast camps size of small towns were built in matter of weeks in WW2 where there was barely anything. No side would be using just what it has in the beginning of the war.

But sure, yet again we disagree. There's enough room on those islands to build up various ports and airbases of various size. Yes, tankers would be needed for some distances and some situations. But if China is for example trying to hit Guam/Palau from Okinawa it just recently captured, then the battle for the sea between 1st and 2nd island chain is not 2400/3000 km for US but is roughly 1000-2000 km away for both sides.


In comparison, CASIC is offering a commercial CZ-11 launch for $7.5M, excluding payload/warhead costs.
The CZ-11 is solid-fueled, vehicle launched and supposed to be based on the military DF series.

It can put 1500kg into low-earth orbit, so it can certainly deliver 1500kg to a distance of 3000km for Guam. Or indeed Wake Island or Hawaii.

1500kg is a lot of kinetic rods or ball bearings. And these could be delivered at hypersonic ICBM speeds and/or with a manoeuvring reentry vehicle.

Note that THAAD can't intercept incoming ICBMs. And whilst the SM-3 might be able to intercept, it costs $18M, which means defensive engagements will cost a lot more than the incoming missiles.
Why don't we speculate about rail guns while we're at it? Both sides could appropriate civilian tech. Who knows what a year long war would bring. Yet alone such a war in 10 years time. I say we stick to what is known and what is there today. One could just as easily say US could have 10 000 hypersonic missiles by then hitting all the launch positions. But that's silly. Let's keep this at least a little grounded.
 

AndrewS

Captain
Registered Member
Why don't we speculate about rail guns while we're at it? Both sides could appropriate civilian tech. Who knows what a year long war would bring. Yet alone such a war in 10 years time. I say we stick to what is known and what is there today. One could just as easily say US could have 10 000 hypersonic missiles by then hitting all the launch positions. But that's silly. Let's keep this at least a little grounded.
We already know that the PLARF has deployed the DF-26 missile with a range of 4000km.
The CSBA estimate that there are currently 120x DF-26 missiles with 80 launchers in service.

In comparison, your railgun is still stuck is development.

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CSBA also estimate a DF-26 equipped with a HGV warhead (like we've seen with the DF-17) would have a range of 6000km.

6000km range puts all of your "rear area" islands in the Pacific at risk.
Then the next closest island is Hawaii which is a whopping 8200km from China.

What we don't know is what a DF-26 costs, which is why I tried to extrapolate from the cost of the CZ-11 rocket which is also solid-fueled and TEL launched.

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And it's not the Chinese appropriating civilian missile technology.
The civilian CZ-11 is almost certainly based on existing Chinese military missiles, where the designs and components were given to them.

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You also mention the US military can appropriate civilian tech.
But the USA doesn't have any civilian rockets that are solid-fueled or launched from TEL vehicles.
So the US military can't appropriate technology that doesn't exist.
 

AndrewS

Captain
Registered Member
Logistical support is built up. Vast camps size of small towns were built in matter of weeks in WW2 where there was barely anything. No side would be using just what it has in the beginning of the war.

But sure, yet again we disagree. There's enough room on those islands to build up various ports and airbases of various size. Yes, tankers would be needed for some distances and some situations. But if China is for example trying to hit Guam/Palau from Okinawa it just recently captured, then the battle for the sea between 1st and 2nd island chain is not 2400/3000 km for US but is roughly 1000-2000 km away for both sides.
Why do you think new ports have to be built up?

We're no longer in WW2 where we had mass formations of ships, planes and army divisions.
It's overwhemingly precision strike now.
And civilian cargo ships are now designed to cross the Pacific in a single trip, unlike in WW2.

So the existing port infrastructure should be sufficient, and there shouldn't be any need to build new ports.

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As for airbases, it is the combination of NUMBER and DISTANCE which makes them relevant.
The airbases on the Japanese Home Islands are too close to China as they are all between 800-1300km.
Then there is a 2400km of empty ocean to Guam and the Marianas Islands, which are the next available bases.
That is too far for fighter jets to affect the 1st Island Chain.

China doesn't have this problem, because it already has airbases available at any distance it wants.

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Why do you think the Chinese would want to invade Okinawa?

But if they wanted to invade an island, Ishigaki or Yonaguni would be so much easier because there are barely any civilians or military personnel on these islands.
Plus Yonaguni is much closer to mainland China than to Okinawa, never mind the Japanese Home Islands.

I wouldn't expect many (if any) Chinese aircraft to actually be based at Ishigaki or Yonaguni.
But it would be a good location for aerial tankers to briefly stop, and fill up on more fuel.
If tankers are based 2100km away in the Chinese interior, they'll spend 6hours in transit, and 6 hours for operations.
So they might need to land and refill 1-2 times.
 

AndrewS

Captain
Registered Member
The "few" resupply ships is a myth. Back in the cold war, soviets had NO chance to suffocate the transport ships in the atlantic. There were tens of thousands of ships available to western powers, which would in large part be used for the war effort. Similarly, going after various transport ships would be a failed strategy for China. One needs to find a ship, make sure its the right ship and waste its torpedoes on it. And sure, even if it sinks 30 ships, what then? Go back to base? Hope to survive that whole time? And try to do it again, every 10 or so days? (could it even find 30 targets within a week?) US and Japan have less ships than NATO countries had in 1980s but even the 6000 merchant ships they do have would be A LOT.
Going all with subs, after those merchant ships would mean no nuke subs left for combat ops between the two island chains. Again, not a good strategy for China in my opinion.
We are now going into a situation where there is real-time satellite surveillance of the oceans, which means it is possible to identify ships.

Plus look at an AIS map. You can see there are barely any ships around Guam or Hawaii or Wake Island.
These are all small islands which do not generate much ship traffic.
Therefore any ship traffic is either military or critical to the civilian economy of those islands.

As for a Japan blockade, remember all cargo ships eventually end at a Japanese port only 800km-1300km from mainland China. There's no point using submarines for these targets. It's easier and cheaper to use sea-mines, land-attack missiles or small (unmanned) submarines.

So there's no need for Chinese nuclear submarines to go after your *6000* civilian cargo ships in the middle of the Pacific.

And it is only a few ships.
Consider that Japan only receives 40-50 shipments from crude oil tankers per month.
And that oil tankers are big, easily identified ships, which have to be docked at ports on the Japanese Home Islands.

This all goes back to the question - what does Japan gain from joining the US in a war against China?
 

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