[brytlea]

This is just a photocopy scan, so of course it's not in color. I removed his name, that's the gray bar underneath the flag.

[Joe 6-pack]

That's definitely not Hangul (Korean), but since the flag only has 48 stars, it would have been prior to Vietnam. I'm fairly confident that it's Chinese.

[mnehring]

That appears to be traditional Chinese (not Mandarin). In the seventh column, the second and third kanji appear to be ‘America’. As someone else said, it is pre Vietnam because of the number of stars, so Korea would be logical. I would guess very early Korean conflict because later Blood Chits for Korea had multiple languages and UN flags beside the American flag.

I'm no expert at all but I hope this leads you in a path that may help.