Awww, go easy on poor Jenny. She probably can't read a map do to her publik skoolin'.
And yes, the Mekong (and it's btanches) isn't a border - as so many here have correctly pointed out. It flows SSE from and through Cambodia, to and through Vietnam.
btw, Now they're saying he spent Xmas in Sa Dec, 50 miles away, right (it gets sooooo confusing)? Well gee if he wanted to put himself closer to Cambodia, why not lie really good and say it was Long Xuyen?? That would have been a little better! (gd poser)