Belzec (English: or , Polish: [buts]) was a Nazi German extermination camp built by the SS for the purpose of implementing the secretive Operation Reinhard, the plan to murder all Polish Jews, a major part of the "Final Solution" which in total entailed the murder of about 6 million Jews in the Holocaust. The camp operated from 17 March 1942 to the end of June 1943. It was situated about 500 m (1,600 ft) south of the local railroad station of Beec, in the new Lublin District of the General Government territory of German-occupied Poland. The burning of exhumed corpses on five open-air grids and bone crushing continued until March 1943.Between 430,000 and 500,000 Jews are believed to have been murdered by the SS at Beec. It was the third-deadliest extermination camp, exceeded only by Treblinka and Auschwitz. Only seven Jews performing slave labour with the camp's Sonderkommando survived World War II; and only Rudolf Reder became known, thanks to his official postwar testimony. The lack of viable witnesses able to testify about the camp's operation is the primary reason why Beec is little known, despite the victim number count. Israeli historian David Silberklang writes that Belzec "was perhaps the place most representative of the totality and finality of the Nazi plans for Jews".

The Holocaust in Ukraine took place in the Reichskommissariat Ukraine, the General Government, Crimean General Government and some areas under military control to the East of Reichskommissariat Ukraine (all subdued to Nazi Germany), in the Transnistria Governorate and Northern Bukovina (both occupied with the latter annexed by Romania) and Carpathian Ruthenia (then part of Hungary) in World War II. The listed areas are today part of Ukraine. Between 1941 and 1944, more than a million Jews living in the Soviet Union were murdered by Nazi Germany's "Final Solution" extermination policies. Most of them were killed in Ukraine because most pre-WWII Soviet Jews lived in the Pale of Settlement, of which Ukraine was the biggest part.

According to Yale historian Timothy D. Snyder, "the Holocaust is integrally and organically connected to the Vernichtungskrieg, to the war in 1941, and is organically and integrally connected to the attempt to conquer Ukraine."