https://www.thenationalnews.com/world/2023/05/26/inside-belgiums-operation-blackstone-to-free-vandecasteele-from-iran/
Inside Belgium's 'Operation Blackstone' to free Vandecasteele from Iran | The National
May 27, 2023 - Brussels bypassed prisoner exchange treaty over fears of lengthy legal challenge and instead sought king's intervention
operation blackstone