1. It's not so easy to launch an air strike to an independent country, nowaday, pal !!!
2. if they use that island for their aircrafts to harm you, you could destroy that island as counterattack act.
build long, destroy fast.
3. not only PH and VN, ID and MY, JP also put big money on readiness of navy.
China doesn't want to fight all. They would try to resolve one by one, that's our cure. Solidity.
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solution for this
1. you cooperate well with Japan, Vietnam and USA in exercise. You may give the airbase access to some type of Vietnam aircrafts.
2. build your early warning system by good radar systems ; buy good SAM systems,
even stealth fighters are not harmless, you know. J-15 is just a so so with average capacity fighter
3. Vietnam is developping the guerilla tactic by submersible to sudden attack the enemy at some important sites.
For example, oil rig, frontier island, naval bases. By cooperating well with us, you could have more way to defend and attack together. We are friends and share the same threat.
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Vietnam has several good radar systems could track any movement in Hainan, and Paracels.
The Paracels are non-movable, the coordinates are put into the computer for fast response. It's an easier target compare to an aircraft carrier.
Low tech missiles can reach it easily.