2. Prevent other countries from re-establishing garrisons on the island,
3. Establish China's own garrisons on the islands.
The first step is easy. Just bomb them out of there. It is easy to prevent the Philippines from re-establishing garrisons once they have been evicted. It is only necessary to patrol the area and sink every Filipino ships found in the area. It will be harder to prevent Vietnam from re-establishing garrisons. To do this it will be necessary to destroy the entire military capability of Vietnam. Once the air force and navy of Vietnam have been destroyed, it cannot re-establish any garrisons on any islands. Then China can accomplish the third step of establishing its own garrisons.
China cannot establish garrisons of any islands if Vietnam military and economy aren't totally destroyed first. But it is easy to destroy the Vietnamese military and economy simply by first wiping them out and then keep wiping them out for decades if necessary. China's economy is already 60 times bigger than the Vietnamese economy. As the Chinese economy expands 8 more times in the next 30 years, it will exceed the Vietnamese economy by 480 times. Therefore, Vietnam will be bombed back into the jungles and will not be able to buy any foreign fighters or battleships. It can then only be able to fight China with wooden boats using at the most RPG. China can use them for target practise to train Chinese soldiers and testing Chinese missiles and assorted weapons. Any Vietnamese ships can be sunk outside of 3 mile from its coasts. There will also be a no-fly zone over all Vietnam.
Malaysia and Brunei are no problems. They won't fight China. The Philippines is too corrupt and cowardly. The only country that dare to fight China is Vietnam. But Vietnam is too small to fight China. China can easily destroy it and keep it suppressed. The only thing that is holding China back is the stupidity and the cowardice of the Chinese government.
Yes, my MS degree is in Electrical Engineering and Computer Science.
Sorry to write in English. I can read most Chinese posts here and I can write some Chinese also, but it will take me too much time to write in Chinese and maybe not express myself so well. Hopefully you and others can understand at least the main point of what I'm saying.