A 4-year-old boy caught in the middle of a bitter international custody dispute must return to Singapore with his father, despite claims from his mother that the move would put him in "grave risk" of domestic abuse, a federal appellate court has ruled.

After Lee Jen Fair took her son Shayan to New York from Singapore in violation of a court order, she contended the boy would be harmed by witnessing physical and verbal abuse against her by his father, Abdollah Naghash Souratgar, and would himself be vulnerable to abuse. She also argued that the father could take Shayan to Iran or seek custody in Islamic courts that favor men.