At least according to [link|http://www.vietnamworks.com/news/news_SaigonTimesDaily_Mar0804.htm|this] article, you should expect that they'll try to find out from your references why you left.
Don't say anything you'll regret. You probably should [link|http://www.faqfarm.com/Q/When_a_job_application_asks_your_reason_for_leaving_a_job_and_were_you_ever_fired_what_is_the_best_way_to_answer|answer honestly] in neutral language.
Luck!
Cheers,
Scott.