Why does Vietnam occupy so many South Island reefs?

Those who are at the seaside are the first people to see the rising moon ―― enjoy the advantages of a favorable position.

As Nansha Islands are far away from Chinese mainland and Hainan Island, it is inconvenient to supply and transport. It is impossible for a big ship to go to those small islands, and it is impossible for a small boat to surf. Vietnam is relatively closer to those islands, so first come, first served. Moreover, in the past, China did not attach importance to the protection of maritime rights and interests, especially around the 1990s, when economic construction was the center, maritime rights and interests were ignored. By around 20 10, when China has been able to support an ocean-going fleet to defend its rights, Vietnam has firmly occupied these islands, and armed expulsion is not realistic at this stage. After all, China is still in the stage of peaceful rise.