George Washington left two last wishes for Americans in his farewell letter after he resigned from the presidency: 1. Not to form political divisions within parties and 2. To stay away from foreign affairs. America followed the second point to the best of their ability until the early 1900s, in a period of a American history called the Isolationist Period.
The first isolationist act observed in American history was James Monroe’s Monroe doctrine. The Monroe doctrine was one of the first pieces of U.S. foreign policy that separated America from Europe. It states that North and South America could not be colonized anymore by European nations and attempts at colonization would be viewed as a direct threat directed at the United States of America. The United States also stated that they would avoid meddling in any European affairs.
America’s foreign policy was very much in tune with the Monroe doctrine throughout the 19th century, When the Russians put down the January uprising in Poland and Napoleon asked the Americans to join France in protest to the Russian Tsar, American Secretary of State William H. Seward declined to maintain the policies of the Monroe doctrine. The first major break of the non-interventionist policies came at the end of the 19th century when the United States fought the Spanish-American War and later the Philippine-American War.
The Spanish American War changed American foreign policy forever. Shortly after the Spanish American War ended in 1902, America became involved in World War I in 1917. When the Americans won the war they mediated the peace proceedings afterward; meddling in even more foreign affairs. However, many Americans wanted to hold onto the non-interventionist policies that America had followed before World War I, so Congress passed the Neutrality Acts, which forbade American trade with nations at war. America soon entered World War I though, when Japan bombed Pearl Harbor. After the Communist revolution in Russia, the Americans- motivated by the Red Scare and other generally anti-communist feelings in the United States- perceived Russia as a threat, and began the Cold War. The Cold War lead to the Vietnam War, the Korean War and also, indirectly, Operation Desert Storm and most other American involvements in the Middle East.
If America had returned to its isolationist roots after fighting World War I and World War II instead of trying to mediate peace between European nations, I believe history would have turned out much differently. America would not have to constantly be involved in the Middle East since rebel groups wouldn’t have received American backing and escalated the fighting in Arab Spring conflicts like what is currently going on in the Syrian Civil War. The Mujaheddin would never have been backed by Americans, thus 9/11 may have been avoided. America wouldn’t have had to fight in the Korean War or Vietnam War. In short, so much bloodshed could have been avoided if America had continued to avoid foreign entanglements.