I am French and I used to a soldier in Indochina war. There are many evidence show that Nansha island(Truong Sa and Hoang Sa) belongs to Viet Nam. May be Chinese discovered the island but you have never controlled it. Viet Nam was the fisrt country garrisoned troops in Nansha.
Maybe you are a French, maybe you are a Vietnamese, it doesn't matter.
The French used to be the colony master of Vietnam, thus the Vietnamese later shamelessly want to inherit the French "occupation" on Spratlys. Here you as a French defends Vietnamese garrisoned on Spratlys first. I just find it funny.
In 1933 when French warships visited Spratlys and claimed occupation for the first time, they did mention the Chinese people were staying and working on the islands. If occupation using force at that time is viewed as legal occupation, then it is acceptable if we use force to drive away the Vietnamese to recovery all the remaining islands today.