Not sure. Will have to check.
Per this website about visas,
B-1 Visitors for Business – Specifically Permitted Activities Listed in the FAM
N6.2.– Members of Board of Directors of U.S. Corporation.
An alien who is a member of the board of directors of a U.S. corporation seeking to enter the United States to attend a meeting of the board or to perform other functions resulting from membership on the board.
This suggests that aliens can thus be members of boards of directors of US corporations.
Any real lawyers out there can weigh in!
