1. Modern missile and targeting technology make the survivability of surface ships (especially carriers) questionable. Satellites can easily image surface ships and missiles can hit them from over a thousand miles away. Submarines are a much better investment and carriers may be a terrible waste of money, analogous to battleships in the WWII era. (Generals and Admirals typically prepare to fight the previous war, despite the advance of technology, often with disastrous consequences.)
2. US forward bases and surface deployments are hostages to advanced missile capability and would not survive the first days of a serious conventional conflict. This has been widely discussed, at least in some planning circles, since the 1990s. See second figure below and link.
3. PRC could easily block oil shipments to Taiwan or even Japan using Anti-Ship Ballistic Missiles (ASBM) or Anti-Ship Cruise Missiles (ASCM). This is a much preferable strategy to an amphibious attack on Taiwan in response to, e.g., a declaration of independence. A simple threat against oil tankers, or perhaps the demonstration sinking of a single tanker, would be enough to cut off supplies. A response to this threat would require attacking mobile DF21D missile launchers on the Chinese mainland. This would be highly escalatory, leading possibly to nuclear response.
4. The strategic importance of the South China Sea and artificial islands constructed there is primarily to the ability of the US to cut off the flow of oil to PRC. The islands may enable PRC to gain dominance in the region and make US submarine operations much more difficult. US reaction to these assets is not driven by "international law" or fishing or oil rights, or even the desire to keep shipping lanes open. What is at stake is the US capability to cut off oil flow, a non-nuclear but highly threatening card it has (until now?) had at its disposal to play against China.
The map below shows the consequences of full deployments of SAM, ASCM, and ASBM weaponry on the artificial islands. Consequences extend to the Malacca Strait (through which 80% of China's oil passes) and US basing in Singapore. Both linked articles are worth reading.
CHINA’S ARTIFICIAL ISLANDS ARE BIGGER (AND A BIGGER DEAL) THAN YOU THINK
Beijing's Go Big or Go Home Moment in the South China Sea
HAS CHINA BEEN PRACTICING PREEMPTIVE MISSILE STRIKES AGAINST U.S. BASES? (Lots of satellite photos at this link, revealing extensive ballistic missile tests against realistic targets.)
Terminal targeting of a moving aircraft carrier by an ASBM like the DF21D
Simple estimates: 10 min flight time means ~10km uncertainty in final position of a carrier (assume speed of 20-30 mph) initially located by satellite. Missile course correction at distance ~10km from target allows ~10s (assuming Mach 5-10 velocity) of maneuver, and requires only a modest angular correction. At this distance a 100m sized target has angular size ~0.01 so should be readily detectable from an optical image. (Carriers are visible to the naked eye from space!) Final targeting at distance ~km can use a combination of optical / IR / radar that makes countermeasures difficult.
So hitting a moving aircraft carrier does not seem especially challenging with modern technology. The Chinese can easily test their terminal targeting technology by trying to hit, say, a very large moving truck at their ballistic missile impact range, shown above.
I do not see any effective countermeasures, and despite inflated claims concerning anti-missile defense capabilities, it is extremely difficult to stop an incoming ballistic missile with maneuver capability.
More analysis and links to strategic reports from RAND and elsewhere in this earlier post The Pivot and American Statecraft in Asia.
... These questions of military/technological capability stand prior to the prattle of diplomats, policy analysts, or political scientists. Perhaps just as crucial is whether top US and Chinese leadership share the same beliefs on these issues.
... It's hard to war game a US-China pacific conflict, even a conventional one. How long before the US surface fleet is destroyed by ASBM/ASCM? How long until forward bases are? How long until US has to strike at targets on the mainland? How long do satellites survive? How long before the conflict goes nuclear? I wonder whether anyone knows the answers to these questions with high confidence -- even very basic ones, like how well asymmetric threats like ASBM/ASCM will perform under realistic conditions. These systems have never been tested in battle.
The stakes are so high that China can just continue to establish "facts on the ground" (like building new island bases), with some confidence that the US will hesitate to escalate. If, for example, both sides secretly believe (at the highest levels; seems that Xi is behaving as if he might) that ASBM/ASCM are very effective, then sailing a carrier group through the South China Sea becomes an act of symbolism with meaning only to those that are not in the know.