Why we need to defense these islands when we can directly deal with US heartland?, we can very well applied the 擒賊擒王 stratagem, US is not beyond China's reach as Japan tried to do in WW2, Japanese couldn't do a jack to US heartland but China can nowadays, and remember this US has never been invaded or attacked, Americans wouldn't be resilience as Chinese which had faced historical wars devastation and able to stand up, do Americans can endure the suffering as Chinese?
Actually, Japan have ways to (and did touch the US mainland) if they have a way to attack Hawaii, and Alaska, they have the mean and way to attack the US Mainland.
The problem is, touching and invading is two different concept. You can bomb (or touch)a country without any direct access route, it's all about mobility and ingeniunity, but to invade someone, there have to be a direct route to have troop on the ground. Even at the begining stage of WW2, US have ways to touch Japanese Homeland, even the closest base is 2000 nautical miles away in Hawaii and Australia, that's what Doolittle Raid is for. Show that US can touch Japanese Homesland, but back then did US have a way to invade Japan? No.
Hence, the question is, what can you do versus what can they do. And in a conventional scenario, China best can do is lob cruise missile over at US Mainland via sub or surface ship or uses the sole carrier to try and bomb US mainland, other than that, there are pretty much nothing Chinese can do. On the other hand, what can US do? US can not only bomb and lob missile, they can also send bomber in for strategic bombing, ambiphious assault, airborne assault, air mobility assault, and all kind of attack toward China, as US have a physical mean to reach Chinese mainland. And the American don't need to win a war in Mainland Chinese to create maximum destruction.
So if you are a Chinese leader, you will have to weight what is the pros and cons, unless China are willing to send nuclear missile over a few Chinese rock in SCS, which translate to Chinese will lose the lot just for some rocks. Or they will lose big in a war with US. Simply because Chinese mainland can be invaded by US, and US mainland cannot be invaded by China.
Again about the would American be able to suffer? Well, as a soldier my self, I did not join the MIlitary because I am patriotic (I am the least patriotic toward the US) I join because that is my job, and I want to do my job. That's why that is called Professional soldier. When you sign up, you have already prepared to be killed and suffer during hardship, that comes with the job title, I cannot say for the whole US Armed Forcees, but majority of the US Armed Force will go fight a war as told, regardless on who they were fighting, there are people sign up during cold war expecting a fight with Russia, there are people sign up expecting a fight in Veitnam, there are people sign up expecting to fight in Korea, Iraq, Afghanistan, Panama, Grenada, Somalia. Fighting is fighting, what makes China different? That is what and why these people sign up.
I cannot say, as I am not a policy maker, that would US will in anyway or form or how to attack China, but if that order is given, there will be an attack, and there will be an attack in full force.
By the way, US have been invaded twice, once by Britain in 1812 and another time by Mexico in 1860s
Don't worry how China will defense those island in SCS. They sure will defend those island with every arsenal they posses.
Those island consist of military grade airfield, that just mean those island can and will be heavily patrol by China naval fighter if need arise. Control of SCS is the must for China national security, those island allow China to confront US at the point of attack further away from mainland China, naval warfare nowhere for US navy to hide without expose their position when attack those island. They only way to preemptive air strike on those island and fully declared war against China by the US.
That is not a plan, that is a "hope" and "Wishful Thinking"
You are expecting the Airfield to to the job, with what and how? How long is the defensive perimeter for each airfield, were they mutually supported? Can these airfield receive replensihment regularly so they can keep their fighter fuelled and armed? Those are just a few but important question you failed to explain.
What you are thinking is "Hope" the higher up will be taken care of these, let that be someone else problem. The question is, Chinese Navy isn't really that big, they cannot absorb even a half strength US Navy, and when you put US aliies in the region, that would mean there are virtually no hope for China to survive a naval engagement. The Sea and Airlane would be close and air interdiction will be at full extend, when you cannot supply food, fuel and ammunition to these Island when the US Navy cut off your supply, how do you plan on defending these island?
Quoting Commandore Quinlan from the Movie Jadotville "With What? With a firm tone?"
, "没吃过猪肉，还没见过猪跑？"
