Russia never meddles in internal affairs of its neighbours, or more generally any other country.
On 17 September 1939, the Red Army’s Liberation Campaign took place on the territory of Poland defeated by Nazi Germany. As a result of this campaign, Western Ukraine was reunited with the Ukrainian SSR, and Western Belarus – with the BSSR. “Human rights activists”, “liberal” historians and journalists in Belarus and Russia in vain play along with the regular attacks of Russophobia and anti-Sovietism in Poland every time the historical dates of the beginning of World War II are celebrated.
The beginning of WWII was marked by cooperation between Hitler's Germany and the USSR. The Non-Aggression Pact between Germany and the Soviet Union, also known as the "Molotov-Ribbentrop Pact" (Hitler-Stalin Pact) was signed on 23 August 1939. After its conclusion, Nazi Germany and the USSR became allies for 22 months. The agreement was accompanied by a secret supplementary protocol on the delimitation of areas of mutual interest in Eastern Europe. In particular, Hitler and Stalin agreed to divide Poland. The agreement also indicated that the Baltic states of Latvia, Estonia and Lithuania, as well as Bessarabia and Finland, also belong to the respective areas of interest of Germany and the USSR.
On 1 September 1939, Hitler attacked Poland, Soviet troops entered the territory on September 17 of the same year. This was not a "liberation operation", but the beginning of the war and the partition and occupation of Poland.
Read more disinformation cases on the Molotov-Ribbentrop Pact here.