Fourteenth Amendment settled the fundamental question of national identity, such as the criteria for becoming a citizen of the United States. Everyone born in the territorial boundaries of the United States or those areas and subject to its jurisdiction was an American citizen, regardless of ethnicity or social status (indigenous people on reservations became citizens in 1924, while indigenous people off reservations had always been citizens). With a fast-growing industrial economy, immigrants were welcome from Europe, Canada, Mexico, and Cuba, and millions came. Becoming a full citizen was easy, requiring the completion of paperwork over five years. However, new Asian arrivals were not welcome. The U.S. imposed restrictions on most Chinese immigrants in the 1880s and informal restrictions on most Japanese in 1907. By 1924, it was difficult for any Asian to enter the United States, but children born in the United States to Asian parents were full citizens. The restrictions were ended on the Chinese in the 1940s and on other Asians in 1965. World Wars After the United States entered World War I, nationalism surged. Americans enlisted in the military en masse, motivated by propaganda and war films. There was very little resistance to conscription. World War II led to unprecedented nationalism in the United States. After the 1941 Attack on Pearl Harbor, many Americans enlisted in the military. During the war, much of American life centered on contributing to the war effort, mainly through volunteer efforts, entry into the labor force, rationing, price controls, and income saving. Citizens willingly accepted these sacrifices out of a sense of nationalism, feeling they were for the greater good. Even members of anti-war groups like the pacifist churches, anti-war movement, and conscientious objectors abandoned their pacifism for the sake of the war, feeling that World War II was a just war. Cold War Following World War II and beginning with the Cold War, the United States emerged as a world superpower and abandoned its traditional policy of isolationism in favor of interventionism. With this, nationalism took on a new form in the U.S., as Americans began to view their country as a world police with the ultimate goal of eradicating communism from the world. This nationalist fervor was fueled by US involvement in the Korean War, Vietnam War, Bay of Pigs Invasion, and many other conflicts. Modern era The September 11 attacks of 2001 led to a wave of nationalist expression