Foreign credit cards will not affect your US credit history what so ever, they are solely based on your SSN and foreign banks cannot use that, nor would they report to the same credit bureaus.

On a similar note, it may be difficult for you to get credit cards as a new resident because you lack a credit history. If you currently have a US Amex give them a call as many times they can transfer your account or modify it to a foreign one as soon as you have your residency papers.