I AM A U.S. CITIZEN, PLANNING FOR VACATION TO PHILLIPINES, THEN VISIT VIETNAM, FROM THE PHILIPPINES, DO I NEED A VISA, AND CAN I APPLY FROM HERE IN THE U.S.
You have three options to apply for your visa in this case:
1 - contact the local embassy of Vietnam in the US to obtain your visa before you go
2 - Apply for a visa through the embassy of Vietnam in Philippines
3 - Apply online for an approval letter to pick up your visa upon arrival.