Israel
Immigration to Israel during the late 1940s and early 1950s was aided by the Israeli Immigration Department and the non-government sponsored Mossad LeAliyah Bet ("Institution for Illegal Immigration"). Both groups facilitated regular immigration logistics like arranging transportation, but the latter also engaged in clandestine operations in countries, particularly in the Middle East and Eastern Europe, where the lives of Jews were believed to be in danger and exit from those places was difficult. Mossad LeAliyah Bet continued to take part in immigration efforts until its disbanding in 1953. An influx of Holocaust survivors and Jews from Arab and Muslim lands immigrated to Israel during the first 3 years and the number of Jews increased from 700,000 to 1,400,000, many of whom faced persecution in their original countries. The immigration was in accordance with the One Million Plan.

Q: The immigration was in accordance to what?
One Million Plan