Picture this: Your ex-spouse takes the children without warning and moves to a foreign country. This nightmare becomes reality for all too many parents. What do you do if your children are now thousands of miles away with your ex? Fortunately, parents are not entirely powerless in this situation. International child abduction is a serious problem that the international community has taken steps to address. Abduction is principally addressed by an international treaty titled "The Hague Convention on the Civil Aspects of International Child Abduction." This treaty is a formal agreement between 73 member nations, including the United States and other nations such as the U.K., Korea, and Brazil.
Under the terms of the agreement, children who are taken from their home country without the consent of one parent, or wrongfully retained by the offending parent must be returned to their home jurisdiction immediately.
There are exceptions to this rule, based primarily on fleeing from domestic violence and things of that nature, but in general if a child is being withheld outside of its home state jurisdiction, the foreign court (in the place where the child is located) is treaty-bound to immediately determine if the home state's (country's) jurisdiction has been usurped and, if so, order the immediate return of the child back to that jurisdiction.
Note that the foreign country is not charged with determining custody; that is, it is not there (in this instance) to decide who the better suited custodial parent is. Rather, its job is simply to decide which court should make that determination, theirs or the "home state" court, and then to enter orders to implement that decision. Often times the United States is the "foreign court," and in that context it is not at all unusual for the United States court to order that a child be returned to the "home state" country, who's courts will then make the ultimate decision of who and how custody should be shared.
Countries that are a part of the treaty can enforce compliance using their respective courts and systems of law enforcement. Parents may still have difficulty getting their children back, but the Hague Convention provides a tangible starting point for their efforts. There are time limitations to be met, however, so it is imperative that a parent who's child has been wrongfully removed from its "home state" jurisdiction, or who may have been allowed to leave but is now being wrongfully retained away from home act quickly to assert and protect these jurisdictional rights, rights that can and often are lost if they are not pursued swiftly.