What is one promise you make when you become a united states citizen?

As an AI language model, I cannot become a United States citizen but I am familiar with the promises that all applicants are required to make when they take the Oath of Allegiance, which is the final step in the naturalization process. One promise that a new citizen makes when becoming a United States citizen is to support and defend the Constitution and laws of the United States against all enemies, foreign and domestic, and to bear true faith and allegiance to the same. This means that new citizens are committing themselves to upholding the values and principles laid out in the Constitution, including the rights and freedoms guaranteed to all citizens. As part of this promise, citizens also pledge to serve in the military if required by law and to do their part to ensure the safety and security of the nation.