The very dependence of the government-in-exile on the British was a source of much tension, and Peter in 1942 tried to involve the Soviet Union and the United States as counter-balances. In 1942 Peter made a diplomatic visit to America and Canada, where he met American President Franklin D. Roosevelt and Canadian Prime Minister William Lyon Mackenzie King. The whirlwind tour was unsuccessful in securing Allied support for the exiled Yugoslav monarchist cause. Roosevelt and Churchill had already engaged the support of the Communist Yugoslav Government in the Allied effort to defeat Nazi Germany, with a view to ending the Second World War. Roosevelt made Yugoslavia eligible for Lend-Lease aid during Peter's visit, but given the small size of the Yugoslav forces in exile, this was not of much assistance. During his visit to the United States, King Peter met the Serbian-American scientist Nikola Tesla on 8 July 1942 and wrote in his diary: "I visited Dr Nikola Tesla, in his apartment in the Hotel New Yorker. After I had greeted him the aged scientist said: 'It is my greatest honour. I am glad you are in your youth, and I am content that you will be a great ruler. I believe I will live until you come back to free Yugoslavia.' From your father you have received his last worlds: "Guard Yugoslavia. I am proud to be a Serbian and a Yugoslav. Our people cannot perish. Preserve the unity of all Yugoslavs - the Serbs, the Croats and the Slovenes."