The Zionists imprisoned by Soviet authorities were allowed to choose sentences of permanent departure to Palestine, where they helped build Jewish society, the backbone of left-wing parties, and the powerful trade union movement.
The Bolshevik leadership was opposed in principle to the idea of creating a ‘Jewish national enclave’ in Palestine. However, the proposal to transport
European Jews to Palestine via the USSR was not implemented and by 1934 the flow of emigrants from the Soviet Union to Palestine had stopped completely. Members of Legal Hechalutz were directed to protest their arrests on the grounds that their organization was not anti-Soviet and had not been banned in the USSR. The policy of substitution may also have been influenced by considerable pressure applied by international Jewish organizations and the Jewish communities of Europe to end persecution of Zionists. The decision by Soviet authorities to allow sentences of internal exile to be substituted for emigration to Palestine set in motion a ten-year ‘exodus’ of convicted Zionists to Palestine. Pompolit raised funds and collected clothing, medicine and food which was sent in parcels to prisoners and those in exile.
https://www.taylorfrancis.com/books/edit/10.4324/9781315039442/exil...