While the Hague Convention can help to get a child returned it is only applicable when the country where the parent has fled with the child is a signed member to the convention. China, Japan, Korea and Taiwan are not. Most Muslim countries on not members of the convention. While Mexico is a member of the Convention, the country is not compliant and you will not receive any help in getting your child returned to the United States from Mexican officials. If your spouse is a national of any of these countries you should discuss with your attorney getting a very strict custody order in place which prevents the parent from taking the child to the country even for vacation.