For purposes of applying this part with respect to a pension, profit-sharing, or stock bonus plan described in section
401
(a) or an annuity plan described in section 403(a), of an American employer (as defined in section
3121
(h)), an individual who is a citizen or resident of the United States and who is an employee of a foreign affiliate (as defined in section 3121(l)(6)) of such American employer shall be treated as an employee of such American employer, if—