That is what the Hankyoreh is claiming that Chinese military planners are planning for:
China is ratcheting up the tenor of its opposition to the possible deployment of a Terminal High Altitude Area Defense (THAAD) system on the Korean peninsula in the wake of a recent visit by Assistant Minister of Foreign Affairs Liu Jianchao. Meanwhile, South Korea and the US are responding on increasingly firm notes. After previously sending the cautious message that nothing had been decided or discussed, they are now bluntly insisting that Beijing keep out the matter. US Forces Korea also looks to be speeding up its preparations, delivering its first confirmation of recent surveys of THAAD candidate sites. It is still too early to tell what the specifics of Beijing’s response will be. But it appears unlikely to remain passive if the US deploys THAAD, a missile interception system, on the Korean Peninsula, as China sees it as a threat to key military security interests.
Beijing has yet to speak publicly about the specific reasons for its opposition. But its concern appears to be that the USFK system is a response to its own A2/AD strategy for preventing the introduction of US troops in the event of an emergency. A2/AD, which stands for “anti-access/area denial,” is a strategy for preventing US troops from accessing sites like Taiwan or the Senkaku Islands (called Diaoyu in China) under an emergency scenario (anti-access) and preventing effective mobile operations by US forces (area denial). As part of the strategy, China has reportedly developed and deployed the Dong-Feng 21 (DF-21) ballistic missile, new anti-ship cruise missiles (ASCMs), and nuclear-power submarines and drafted scenarios for preventing US naval and air forces from reaching a second island chain (maritime defense line) and first island chain.
The focus of attention for many is the inclusion of both US bases in South Korea and Japan as targets for A2/AD strikes. China is also reportedly working on a strategy for potentially ambushing and knocking out Air Force bases in Osan, Gyeonggi Province and Gunsan, North Jeolla Province, which it fears could be used as scrambling bases for US aircrafts. China’s concern has long been that USFK bases could be used against it, rather than simply as deterrents against North Korea. Its fears were fanned after South Korea and the US reached a “strategic flexibility” agreement in Jan. 2006 that guaranteed free access to the peninsula for USFK. The move was an official signal that USFK was not just a fixture of the peninsula, but a force that could be deployed anywhere to suit US needs. [Hankyoreh]
You can read more at the link, but if China is planning to attack USFK bases in a Taiwan contingency it seems it would further justify why additional missile defense assets are needed on the peninsula, not less.
