How can I legally prove that my wired money is legal in the US?
We cannot give legal advice. The following is not a substitute for the advice of a local attorney. But we hope the information will be useful.
Once your money has been converted to US Dollars and transferred from your account at a Vietnamese bank to your account at a United States bank, there is little else you need do. The US bank can issue you a cashier's check at that point, and it is legal tender. Or the US bank can otherwise verify to the seller that the money is present in the account.
A middle-man US bank may be needed, a large bank that holds a reciprocal account with the Vietnamese bank. Then this middle-man bank can make the final transfer to your local bank.
Your local bank representative should be able to guide you through the transaction with relatively little difficulty.
For more information on international wire transfers, see these links: