Border outpost
outpost maintained by a sovereign state on its border, usually one of a series placed at regular intervals, to watch over and safeguard its border with a neighboring state
en-US/ˈbɑɹdɚ ˈaʊtˌpoʊst/
en-GB/ˈbɔːdə ˈaʊtpəʊst/
outpost maintained by a sovereign state on its border, usually one of a series placed at regular intervals, to watch over and safeguard its border with a neighboring state