Odd situation: My 5 year old son has dual Thai-American citizenship. His American passport is valid, but his Thai passport has expired and we are having trouble renewing his Thai passport due to problems with registering address. We will travel outside of Thailand and return. What problems are there if he leaves Thailand and enters Thailand with only his American passport? He has traveled outside of Thailand but in the past he stamped in and out of Thailand with his Thai passport. He does not have a departure card in his American passport, or any entry or exit stamps.