To be very brief, it is because the interests of the US have become so broad that it is now necessary to protect them in one way or another all over the globe. Immediately after the Revolutionary War, George Washington stated that the US would stay out of Europes' intrigues and squabbles. England and France were always fighting. He wanted to concentrate on America's growth. From the time of William the Conqueror, nations allied themselves with other nations to make themselves stronger. Washington wanted to avoid these entanglements. As the country grew, its interests expanded into other parts of the world. Trade and politics were and are the basic moving forces. The US needs oil, so it looks to keep things settled down in the Middle East. It needed to avoid war with the Soviet Union after WW2, so it created NATO and strengthened Germany so Germany could be a barrier to Soviet aggression. It wanted to suppress the spread of communist regimes to friendly democratic countries so it went to war in southeast asia. Now the US is heavily dependent on foreign trade, so it must stay on friendly terms with other nations. The whole world has become a smaller place and events in other parts of the world that would have had no effect on colonial America now have serious consequences on modern America.
the shift of isolationism to internationalism the shift of isolationism to internationalism
America was bombed at pearl harbour, and Hitler declared war on America the next day.
Internationalism
How did the US go a isolationism foreign policy to a political and military involvement?
isolationism
the president and his chief advisers are the principal architects of U.S. foreign Policy.
isolationism
Isolationism
Internationalism
America's ealry foreign policy tended toward isolationism.
isolationism
Isolationism