What can I do to get my children back to Israel ,where we live,after their mother secretly boarded a flight with them to France?

Bring Hague Convention child abduction proceedings for their return from France to Israel.Both states are bound by the 1980 Hague Convention on the Civil Aspects of Child Abduction, through which a return order can be requested ordering the minors back to the country of habitual residence. Your wife's removal of the children from Israel ,without your consent, was wrong, and an act of child abduction.