Except as otherwise provided by treaty or this chapter, whenever compensation is payable to a beneficiary who is an alien not residing in the United States, the department shall pay the compensation to which a resident beneficiary is eligible under this chapter. But if a nonresident alien beneficiary is a citizen of a government having a compensation law which excludes citizens of the United States, either resident or nonresident, from partaking of the benefit of such law in as favorable a degree as herein extended to nonresident aliens, he or she shall receive no compensation. No payment shall be made to any beneficiary residing in any country with which the United States does not maintain diplomatic relations when such payment is due.