The Northern Group of Forces (Северная группа войск; Północna grupa wojsk) was the military formation of the Soviet Army stationed in Poland from the end of Second World War in 1945 until 1993 when they were withdrawn in the aftermath of the fall of the Soviet Union. Although officially considered Polish allies under the Warsaw Pact treaty, they were seen by some Poles as a Soviet occupation force.
Soviet forces entered Poland as they were advancing towards Nazi Germany in the course of the Red Army's Operation Bagration in the summer of 1944. Following the Vistula-Oder Offensive in early 1945, all of Poland was liberated from Nazi occupation by Soviet forces. While formal Polish sovereignty was almost immediately restored, the territory of Poland fell under de facto Soviet control as the Soviet military and security forces acted to ensure that Poland would be ruled by the Soviet-installed communist puppet government of Poland.
As the war ended, the structure of the Soviet military was reorganized from a war-time to a peace-time mode. Directive No. 11097 of 10 June 1945 created several new formations, known as Groups of Forces, equivalent to military districts, but used for command and administration of Soviet forces outside the Soviet Union itself. One of those new formations, at that time 300,000-400,000 strong, was to be stationed in Poland. It was mostly based on the 2nd Belorussian Front of General Konstantin Rokossovsky (formerly stationed around Mecklenburg and Brandenburg). With the exception of Szczecin (Stettin), which fell under the operational territory of the Western Group of Forces, the Northern Group of Forces was located entirely within the territory of Poland.
The Polish communist government, which largely owed its existence to the Soviets (see Polish Committee of National Liberation, 1946 Polish people's referendum, 1947 Polish legislative election), signed several agreements with the Soviet Union regulating the status and purpose of the Soviet troops.