“American employer” means any of the following:
(a) An individual who is a resident of the United States.
(b) A partnership, if two-thirds or more of the partners are residents of the United States.
(c) A trust, if all of the trustees are residents of the United States.
(d) A corporation organized under the laws of the United States or of any state.
(e) A limited liability company organized under the laws of the United States or of any state.
(f) Any Indian tribe as described by subsection (u) of Section 3306 of Title 26 of the United States Code.