which of these events occurred first during the summer of 1945?\nthe soviets joined the pacific war.\ntruman…

which of these events occurred first during the summer of 1945?\nthe soviets joined the pacific war.\ntruman gave japan an ultimatum to surrender.\nthe first atomic bomb was dropped.\nthe second atomic bomb was dropped.
Answer
Answer:
Truman gave Japan an ultimatum to surrender.
Brief Explanations:
Truman issued the Potsdam Declaration ultimatum on July 26, 1945. The Soviet - Union joined the Pacific War on August 8, 1945. The first atomic bomb was dropped on Hiroshima on August 6, 1945, and the second on Nagasaki on August 9, 1945. So Truman's ultimatum came first.