The correct answer to this open question is the following.
The Declaration of Independence provides a reason to revolt against Britain based on a promise that a new government will be able to secure the natural rights of its citizens. The government of the United States has done this to the extent that it has protected the American people since then in many different wars against Britain in the War of 1812, or the Mexican-American War, or the Spanish-American War.
During the 1900s, the United States government tried to maintain the foreign policy of neutrality in World War I and World War II, but different events and incidents forced President Woodrow Wilson and Franklin D. Roosevelt, respectively, to enter the international conflict in order to defend America from the threat of Germany.
The only questions left unanswered are regarding domestic politics such as racism, inequity, civil rights for minorities.