You need a bank with a presence in VietNam preferably. The alternative is a US bank with discount or free ATM access.
I would have recommended HSBC but they have become real a*seholes with their new Secure(sic)Key which isn't. This is needed with every InterNet banking transaction as well as every ATM transaction.
eventually it is a code generating device into which you key a number provided by the SK computer and displayed on whatever screen.
You then watch the magic SK device spit out a new number which you may or may not be able to read as the font size is too small or cannot be read as the ambient light is too low, which is keyed like a PIN.
Three attempts and you are locked out and requires a phone call to your HSBC to answer some inane questions and, eventually, they reset your account.
One of my HSBC accounts is now in it's 23rd day of lock-out as they try to sort the problem. Basically they could care less about customers these days.
So be careful what bank you select.
The way I arrange my ATM accounts is to have a savings account in to which deposits go. This has no ATM access and is used simply as a medium from which to transfer money to the ATM account or make electronic payments.
The associated banking account has ATM access. Before making a withdrawal I look at XE.com and have it calculate how many US dollars I need to buy X-amount of VND. I transfer that amount rounded up by USD$5 to ensure any exchange rate differences occur.
I then make my withdrawal leaving a minimal amount for hackers.
This damn stupid Secure(sic)Key will be used throughout the HSBC system, so now is the time to get a bank that doesn't use it.
This stupid Secure(sic)Key can only be used for one account, unless it is a business account when, magically, their computer can handle more that one Secure(sic)Key. This means shared accounts have to arrange access to the Secure(sic)Key. If you are in Seattle and your favourite squeeze is in Sacramento, one of you will have no access to money.
A brilliant scheme. Is not actually secure from hackers but it does effectively prevent customers from accessing their money easily.
Some countries have two levels of pension payments, a bonus paid upon where you reside. This can easily be circumvented by having the receiving account of the pension transfer the amounts to your double savings/banking account. Not exactly impervious to investigators but answers casual inquirers information, including credit bureaus.
If you wish to transfer lump sums of money in to VietNam use a SWIFT transfer. This system provides documentation sufficient to satisfy the State Bank of VietNam you actually brought the money in.
Just remembered another reason to avoid HSBC. They claim they can only disburse transfers in VND, which means they screw you on the exchange rate and steal your dollars. They also say the State Bank of VietNam requires this.
They lie.
Other banks in VietNam will give you USD$ or AUS$, in cash, when you pick the money up. ANZ allegedly hands out hard currency.
But why would anyone trust HSBC given they had a big laundry operation washing Mexican drug money in the USA or they were one of the banks allegedly (!) fiddling the Euribor overnight interest rate.
Hope this helps.