After the first World War, the United States had entered a 10 year span of great isolationism. They had completely stayed away from European entanglements and had even passed tariffs to disencourage trade with Europe, most notably the Hawley-Smoot tariff. This great isolationism was also adopted to prevent another war. The effects of this isolationism were that first, another war wasn't prevented and second, the tariff played as a major cause for the Great Depression, so obviously the policy of isolationism didn't work. The American government needed a new policy so these problems don't happen again and through the process of WW2, as America became the strongest world power, they were able to adopt the policy of interventionism. Adopted by Truman against the Soviets to prevent the spread of their communist ideas, we first saw this new policy in the Korean War and then again in the Vietnam War, when we intervened to attempt to halt the spread of communism there. The second World War caused this policy change because of the world-superpower-status that America had achieved through the war and as WW2 brought America out of the Great Depression, the American government needed a new policy because obviously isolationism hadn't worked, so to prevent another depression, the government changed radically to the other side.
One of the reasons that America had emerged a world power after the war is because of its large advancements in science and technology through the war. The development and usage of things like more advanced airplanes and ships, radar, better guns, and even the nuclear bomb had caused America to emerge a technological superpower also. This spur of science didn't just stop after the war; it continued well into the 1950's and 1960's. Many of the technologies developed for warfare were brought to the standard American home while others were used for further military development. A notable example of the latter was shown in the U-2 incident in the Soviet Union when the Soviets found out about a stealth airplane that America had developed. Although this stealth airplane was caught, it is significant in showing that Americans were working very hard to perfect military technologies. The science boom wasn't limited to just the military, but it did seem to revolve around competing with the Soviets. The Soviets launched Sputnik, the first satellite a few year just after WW2 and the Americans quickly responded through NASA. Through this boom, America was able to send the first man to the moon, a lot because of old Soviet sentiment.
