Discussion on:

Creating a forest level trust relationship in Windows Server 2003

How to configure trust relationship between two doamins

This may be related, or not.

I currently have a domain trust setup between server1 in US and server2 in China. Trying to have users in China be able to log in with their credentials for their domain into US. From there need to share ability to edit a dB within the US domain in a program. Any points in the right direction?