If the debtor has assets such as real estate or vehicles but refuses to voluntarily execute the judgment, the enforcement agency can take compulsory measures to seize and value these assets for auction, and use the money to execute the judgment according to the judgment's decision.
In addition, according to Clause 4, Article 36 of the 2019 Law on Citizens' Exit and Entry, those who are obliged to execute a judgment but evade or embezzle assets will have their exit temporarily suspended to prevent them from leaving Vietnam before completing their obligations.
Therefore, your debt defaulter will not be allowed to leave the country without fulfilling his obligations.