That would definitely move your marriage outside the jurisdiction of any of the 50 states or U.S. territories. Even if you were stationed overseas as U.S. military you could file in the United States but if you wanted the states to regain jurisdiction over the marriage, one of you would have to relocate back to the states.
Each state has its on residency requirements. Some states require extended residency (up to two years), but some states are minimal--Alaska, for example, only requires that you reside in Alaska at the time of filing (with no duration requirement).
With both of you living in Ho Chi Minh City in the private sector since 2007, no state or territory (and, as far as I know, no other country) will recognize jurisdiction over your marriage. You will need to divorce in Vietnam, or relocate.
I understand that you may have follow-up questions. Let me know if further clarification is needed, and please keep in mind that the experts are not credited for unaccepted answers; even where I cannot solve every problem in a case, my hope is that you can at least feel confident in your knowledge of your rights so you can get the best legal outcome under the circumstances, whatever that outcome may be. Thank you.