The SCS dispute is not only between China and the US:
Not only China build bases on islands in the SCS:
Who did it first?
Malaysia.
Swallow Reef, known now as Pulau Layang-Layang;
Reclamations started in the1980s to create a naval base.
According to a former Malaysian Navy Commander I worked with they had found a rock that was above water at HW and thus qualified as an island by UNCLOS and claimed it for Malaysia.
It still have legall status as “Rock”:
Swallow Reef | Asia Maritime Transparency Initiative (csis.org)
Now with an airport and a well known dive resort: