DVD regions and international military bases

[Celeval]

Pretty random question, which I suppose makes it a good candidate to be asked here.

My brother-in-law is military and he and my sister live just off a base in Japan. They do a decent bit of traveling, so we're considering getting them a portable DVD player for Christmas; but don't know if we have to worry about region codes and the like - if either most portable players don't have a way to switch codes, or if they have a mix of DVDs, or if it even matters. Anyone have any experience or advice?

[Raiders Army]

I only have been deployed to SWA; however, I found that the PX/BX has US region DVDs. The DVDs that are sold on the "black market" (i.e. downtown Riyhad or Kuwait City) are US as well.