單身老貓 and anyone, please help!

My ex hu*****and is considering working out of country for two years and he told me our boys can visit him during summer and winter break in that country and his parents can help take care of the boys. Right now, we live about 40 minutes away and he sees the kids one day of every week. I told him I had never been to that country before and I do not want to take any risk to send my boys for a foreign country no matter how safe he claims. Can I prevent my boys to visit their dad out of country? Their dad is welcome to visit the boys whenever he is in United States. I am in Texas. Any advise, please?