The state border of Belarus separates Belarus from 5 states and has a length of .[1]
The incorporation of Western Belarus to the USSR radically affected the state of protection of the state border with Lithuania by parts of the Belarusian District. After the accession of Western Belarus to the BSSR on October 15, 1939, the border detachments of the People’s Commissariat of Internal Affairs (NKVD) of the BSSR was tasked to guard the Belarusian section of the border with Germany, and on June 21, 1940, also the Lithuanian border. The former Soviet-Polish border was not fully dismantled and existed up until the German attack on the Soviet Union. For internal security purposes, the servicemen of the Belarusian border district carried out security service on the “old border”, for the passage of which the population needed special passes.
| Country | data-sort-type="number" | Length (km) | Notes |
|---|---|---|---|
 Latvia | 172.912 | Part of the . | |
 Lithuania | 678.819 | Part of the . | |
 Poland | 398.624 | Part of the . | |
| All area: | 1,250.355 | ||
| 1,283 | |||
 Ukraine | 1,084 |