Which is why Winston Churchill famously said in 1946 that an iron curtain had descended across Europe. While the dates of the Cold War are usually given between 1945 and 1990, a number of historians will tell you that it actually started during World War II. Japan's distrust of the US and Britain kept growing as they refused to invade Europe and open up a second front against the Nazis. And some even say that the decision to drop the first atomic bombs on Japan was motivated in part by a desire to intimidate the Soviets. That sort of worked, but only insofar as it motivated the Soviets to develop atomic bombs of their own. They successfully tested their first one in 1949. From the beginning, the US had the advantage because it had more money and power and could provide Europe protection, what with its army and one-of-a-kind nuclear arsenal, while Europe rebuilt.