They were US citizens.
Weird legal issue though, 'cause the status was revoked with Philippine independence in 46.
At the time the Phillipines was an US Territory acquired as a result of the Spanish-American War. Independence for the Phillipines had been planned for sometine in 40’s. WWII interrupted the transition. On July 4, 1946, the United States granted the Philippines its independence which surprised many in SEA as other European countries did not do so but instead tried to reclaim their colonies