Guarding the periphery of VietNam, and it's territories (islands) is the Vietnam Border Defense Force with around 150,000 people serving in it.
They carry guns, big guns (rifles) and are part of the VietNam People's Army.
Foreigners soon discover who they are if they enter in to the border exclusion zones that varies between 2 and 5 kilometres in width, usually with a distinct 'click'.
Luckily, they have very distinctive badges. They wear forest green uniforms to blend in with the scenery.
VietNam Border Defense Force
Some internal parts of VietNam are restricted, such as around the border provinces in the northwest, and entry is only permitted by a Permit or hiring a police approved guide. Foreigners breaking these rules, if caught, are usually subject to house arrest in a (real) hotel of the police choosing (think rough conditions and high prices).
Then you get 'deported' to Ha Noi or some other nearby large city!
They also act as 'gatekeepers' on the many small paths and tracks that cross between VietNam and neighbouring countries. Residents from adjacent areas, using an ID card, can cross into the adjacent area in another country, and vice versa.
Foreigners often see the Border Defense Forces at the Khe Sanh border crossing where there are two, consecutive, border check points in view of the amount of stolen motorcycles taken in to Laos. The area in between the two gates is guarded by the Border Defense Forces.
You might also see them patrolling the rivers in the MeKong which is a high volume smuggling route from Cambodia and Thailand.
