On 13 January, 1946, the Decree of the Presidium of the Supreme Soviet of the USSR "On the ratification of the treaty between the Union of Soviet Socialist Republics and the Polish Republic of the Soviet-Polish state border" was issued.

The treaty was signed in Moscow on 16 August, 1945, by the president of the Polish Republic, Edward Osobka-Morawski, and the USSR People's Commissar for Foreign Affairs Vyacheslav Molotov.

The document confirmed the decision taken during the Yalta Conference to establish the border between the two countries along the "Curzon Line", on the territory of present-day Western Ukraine and Western Belarus. Vilnius, Grodno, Brest, Lviv and adjacent regions departed from Poland to join the USSR. Part of the territory of Belovezhskaya Pushcha, located to the east of the border, including Bialystok, remained with Poland.

The treaty entered into force on 6 February, 1946, after the exchange of instruments of ratification in Warsaw. Within 15 days, the Soviet-Polish commission drew the borders on the ground.

In February 1951, the border was adjusted in accordance with the agreement "Concerning the
exchange of sectors of their State territories."

Source: Collection of laws of the USSR and decrees of the Presidium of the Supreme Soviet of the USSR