Children and (most) teens need help to make sense of challenging experiences such as the deployment of a parent. They don’t have the skills yet to work through their feelings on their own, and that’s where parents (or other caregivers) come in.
One method is to talk through your child’s experience and understand it from his or her point of view. Ask open-ended questions such as: “How did you feel when you found out that Dad/Mom was going to be deployed?” Or later in the deployment cycle: “Do you feel different now that Dad/Mom has been gone a while?” Don’t ask questions that supply the answer or can be answered “yes” or “no” (“Are you upset that Dad is away?”).
The amount you talk depends on your children’s ages, of course, as well as their desire to share what they’re feeling. If they don’t feel like talking, don’t force them to. Just let them know you’re available.
And finally: Don’t argue with what your child is feeling. Just let him or her know you’re trying to understand.