This new capability will complicate Taiwan's air defenses:
Russian media reports indicate China and Russia have signed a US $3 billion contract to procure an initial six S-400 battalions. The missile is an upgraded variant of the S-300, now fielded by China in battalions based near major cities and scattered along the coast facing Taiwan and Japan.
Kashin, who attended the recent Airshow China in Zhuhai, said that with a range of 400 kilometers and fielded in Fujian Province, the SAM system will be able to cover the whole of Taiwan airspace, thus finally solving the “problem of air superiority for the Chinese.”
While it complicates Taiwanese air defense, it is not necessarily decisive even when paired with China's 1,300 surface-to-surface missiles that can target Taiwan's airfields.
Those SSMs have other targets besides runways and if Taiwan has rapid runway repair capabilities (which they should have), those missiles will hurt but not be decisive.
And relying on S-400s for control of the air over Taiwan means China will not be able to fly their own aircraft over Taiwan out of worry of a too-complicated air space.
Really, does anybody think China can deconflict the air space over Taiwan to the degree that hundreds of planes can be sorted and identified, allowing those S-400 SAMs to shoot down just Taiwanese, American, or Japanese planes?
Further, by deploying such air defense weapons in Fujian province, China puts their homeland in the cross hairs. They can hardly use their territory to attack Taiwan and expect Taiwan (and America, but probably not Japan) to strike such targets.
Without those SAMs, it is possible that a limited war could be fought from China's edge eastward restricted to an area in and over the Taiwan Strait and Taiwan itself.
With those new Chinese SAMs, Taiwan must attack the mainland to hit the missile radars and batteries themselves. And as long as they are doing that, they could attack SSM sites and airfields and ports hosting units that are attacking Taiwan.
Which means that the Chinese will feel the pain of war rather than just watching it on their TVs as something happening to Taiwan.
The new missiles complicate Taiwan's defenses. They also complicate China's attack options. On balance it is surely a Chinese advance, but it is hardly the last word.
In related news, the Chinese are complaining that we will sell Taiwan some old Perry class frigates:
China's foreign ministry rebuked the U.S. Congress on Monday after legislators passed a bill allowing the sale of second-hand warships to Taiwan, the self-ruled island which Beijing claims as a renegade province.
The Perry frigates will be useful in operations off of Taiwan's east coast to hold open sea lines of communication, but are too big to operate in the strait to battle an invasion.
Rather than a splendid little war, China will get an actual war on their own soil if they use force to conquer Taiwan or compel Taiwan to join China.
UPDATE: The need for Taiwan to attack China's mainland military bases is no theoretical exercise, according to a retired Chinese general:
An army general has warned that China will not leave the Taiwan problem "unresolved for a long time", after the island's Beijing-friendly ruling party suffered a bruising election defeat, a state-run newspaper said. ...
"The Taiwan issue will not remain unresolved for a long time. We will not abandon the possibility of using force; according to the law, it is also an option to resolve the issue by military means if necessary," said Liu, a former president of the influential Chinese Academy of Military Sciences.
This is nothing new. And reason for Taiwan to arm up if they want to preserve their island democracy.
Ask Hong Kong how easy it is to retain democracy within China.
UPDATE: Also, relying on new mainland-based SAMs to control the air over Taiwan wastes this extraordinary (for China) level of training:
These recruiting and training changes are part of a trend since the 1990s in which China has been gradually creating a Western style air force. It’s not just with modern aircraft but with modern training methods and tactics as well. While China has only about 600 modern aircraft (comparable to the American F-15/16/18/22), it’s their improved training that is most worrisome. The U.S., Taiwan, Japan, and South Korea have over five times as many such aircraft and well trained pilots. China, however, is rapidly closing the gap. In another decade or so, China will have at least two thousand modern warplanes and, if they keep at it, pilots close to the capability of their Western counterparts.
I'm not sure what role China has in mind for those S-400 missiles, but I think that Chinese aircraft will be used to seize control of the air over Taiwan.