The Niños's fate changed with the start of the Second World War. Soviet interest in the Niños decreased after the end of the Spanish Civil War, and with the signing of the Ribbentrop-Molotov Pact in August 1939, which assured non aggression between the Soviet Union and Nazi Germany. Soon after Germany, and then the Soviet Union invaded Poland, creating a new boundary between the two powers. The pact was fully terminated in June 1941. The Niños houses were dismantled due to the dangers of Nazi invasion. When the German army besieged Leningrad, and moved towards Moscow, and into Ukraine in the south, all the areas where the Spanish children had been placed were compromised. The Niños children in the two houses of Leningrad endured the blockade of the city by the German army during the harsh winter of 1941 to 1942. 300 Niños children were evacuated once the fence could be opened, crossing the frozen lake Ladoga in trucks. Gradually, and with the agreement of the Communist Party of Spain, the different Niños houses were evacuated to areas considered safer, in some cases quite remote, near the Ural Mountains and Central Asia.