@Nihonjin1051 speaks much truth with his recommendation to build up SAM and air defense systems, and I would offer perhaps a more prudent course of action. While the best course is to maintain peace, if peace cannot be found or is not expected, that deterrence is the best way forward. In the SCS aircraft don't fly unless ships cover them. They either lack the range, for interceptors and fighters or they lack the numbers, heavy bombers would fit this criteria, what is needed most is not a system to defeat aircraft, but one to keep enemy shipping far from one's own lands. ASW and AShMs, these are what are needed most. Without air support ships are put at great risk, but without SAM cover, and without ships suppressing coastal and land based air defenses, aircraft are not effective either. Use air assets for anti-missile defense as the most probable weapon to be used against you are long-range cruise missiles, but always be ready to counter enemy surface and sub-surface shipping. One other area of concern is the size of a buildup. Keep in mind that nations in the region are developing longer range UAV and UUV systems that could have the range to make air assets a viable solution to a traditionally sea dominated region. Would a token force be useful? Yes, it would slow an enemy advance, but care must be taken to balance the need to protect something with the cost of deployment and the allocation of funds to more useful measures.