Unless otherwise provided in section 1401 of this title, the following shall be nationals, but not citizens, of the United States at birth:

(1) A person born in an outlying possession of the United States on or after the date of formal acquisition of such possession;

(2) A person born outside the United States and its outlying possessions of parents both of whom are nationals, but not citizens, of the United States, and have had a residence in the United States, or one of its outlying possessions prior to the birth of such person;

(3) A person of unknown parentage found in an outlying possession of the United States while under the age of five years, until shown, prior to his attaining the age of twenty-one years, not to have been born in such outlying possession; and

(4) A person born outside the United States and its outlying possessions of parents one of whom is an alien, and the other a national, but not a citizen, of the United States who, prior to the birth of such person, was physically present in the United States or its outlying possessions for a period or periods totaling not less than seven years in any continuous period of ten years—

(A) during which the national parent was not outside the United States or its outlying possessions for a continuous period of more than one year, and

(B) at least five years of which were after attaining the age of fourteen years.

The proviso of section 1401(g) of this title shall apply to the national parent under this paragraph in the same manner as it applies to the citizen parent under that section.