Spratley Islands are not “foreign territory” since they are claimed, in full or in part, by many countries, based on old historical activity in the area, or based on the EEZ as defined by UNCLOS. (USA has no claim)
Here from Encyclopaedia Britannica:
China claim all the islands, as does Taiwan (as the Republic of China) based on historical activities.
The other claimant (Vietnam, Philippines, Malaysia) make their claim based on UNCLOS and partly history.
Brunei and Indonesia claim some of the waters of the South China Sea as their EEZ, but not any islands or reefs.
The Paracel Islands is different and only contested between China and Vietnam:
http://fact.geoba.se/country-page.php?bc=PG1