https://www.reuters.com/article/us-usa-china-southchinasea-pompeo-idUSKCN24G25U
Yesterday, the Secretary of State Mike Pompeo says the US will support the various countries in their competing claims with China. Although this is too little too late, this symbolic escalation allows both sides to respond to each other with little material costs.
China had already been creating islands, and fortified them with various military facilities. They are militarily worthless though, since they would be vulnerable to missile attacks form various ships. Nonetheless, they can deter the other claimant states from visiting the area, especially the Philippines and Vietnam.