If a father emigrates to another country, will he be held accountable for his two children, aged two and three and a half respectively, who are being raised by their divorced mother in a non-Islamic country?

If a divorce occurs, custody of the two children belongs to the mother, unless she remarries and is qualified for custody. If the father wishes to travel permanently, the father has a greater right to custody. However, if the mother is not qualified for custody, such as being a disbeliever or immoral, her custody is forfeited, and the father must take the children from her.