On May 6, 1943, FDR had offered numerous options for a summit site in a letter to Stalin and concluded, "I suggest that we could meet either on your side or my side of Bering Straits." He said he wanted to meet Stalin one-on-one, with only one staff member and an interpreter, meaning without Churchill. FDR took pride in his powers of persuasion and thought he would do better with Stalin alone.

https://www.adn.com/commentary/article/all-presidential-visits-alaska-one-would-have-captured-world-headlines/2015/08/31/