Initial discussions began to take place in 1938 among Nazi ideologues such as Julius Streicher, Hermann Göring, Alfred Rosenberg, and Joachim von Ribbentrop. Ten per cent of Jews under German jurisdiction by that date were Polish nationals. Józef Lipski, the Polish ambassador to Germany, expressed his country's reluctance to take them back, and the Polish government decreed that Polish passport holders would not be permitted to return except under specific conditions. When Ribbentrop raised the matter with French foreign minister Georges Bonnet in December of that year, Bonnet expressed French reluctance to receive more German Jews and inquired if measures could be taken to prevent their arrival. France itself was contemplating how to deport some 10,000 Jews and considered whether Madagascar might be an appropriate destination. Planning for German deportations to Madagascar formally began in 1940. Franz Rademacher, recently appointed head of the Jewish Department of the Ministry of Foreign Affairs, forwarded on 3 June to his superior, the diplomat Martin Luther, a memorandum on the fate of the Jews. Rademacher said: "The desirable solution is: all Jews out of Europe". He briefly considered Palestine as a destination, but deemed it unsuitable, as he considered it undesirable that a strong Jewish state should be created in the Middle East. In addition, Palestine was under British control at the time. Rademacher recommended that the French colony of Madagascar should be made available as a destination for the Jews of Europe as one of the terms of the surrender of France, which the Germans had invaded on 10 May 1940. The resettled Jews, noted Rademacher, could be used as hostages to ensure "future good behaviour of their racial comrades in America". The plan was developed by Referat D III of the "Abteilung Deutschland".