My ex is trying to take our child out of the country. How can I prevent this?
Call the Passport Services Office of Policy and Advisory Services at 1-202-955-0232 for information on preventing your ex from leaving the country with the child. This is what they will tell you:
Send a written request that the children be placed on a name check system. Send children's names, dates and places of birth, plus Social Security Numbers (if you have them), and any other pertinent information (like a physical description), along with your name, address, and a phone number where you can be reached, to Passport Services.
Make sure you sign the request. You can FAX the request letter to 1-202-955-0230.
More information on this topic is available here: Preventing International Move-Aways.