Section 101(a)(22) of the Immigration and Nationality Act (INA) states that “the term ‘national of the United States’ means (A) a citizen of the United States, or (B) a person who, though not a citizen of the United States, owes permanent allegiance to the United States.” Therefore, U.S. citizens are also U.S. nationals. Non-citizen nationality status refers only individuals who were born either in American Samoa or on Swains Island to parents who are not citizens of the United States. The concept of dual nationality means that a person is a national of two countries at the same time. Each country has its own nationality laws based on its own policy. Persons may have dual nationality by automatic operation of different laws rather than by choice. For example, a child born in a foreign country to U.S. national parents may be both a U.S. national and a national of the country of birth. Or, an individual having one nationality at birth may naturalize at a later date in another country and become a dual national.

U.S. law does not impede its citizens' acquisition of foreign citizenship whether by birth, descent, naturalization or other form of acquisition, by imposing requirements of permission from U.S. courts or any governmental agency. If a foreign country's law permits parents to apply for citizenship on behalf of minor children, nothing in U.S. law impedes U.S. citizen parents from doing so.

U.S. law does not require a U.S. citizen to choose between U.S. citizenship and another (foreign) nationality (or nationalities).  A U.S. citizen may naturalize in a foreign state without any risk to their U.S. citizenship. 

U.S. dual nationals owe allegiance to both the United States and the foreign country (or countries, if they are nationals of more than one). They are required to obey the laws of both countries, and either country has the right to enforce its laws.  Claims of other countries upon U.S. dual-nationals may result in conflicting obligations under the laws of each country.  U.S. dual nationals may also face restrictions in the U.S. consular protections available to U.S. nationals abroad, particularly in the country of their other nationality.   

U.S. nationals, including U.S. dual nationals, must use a U.S. passport to enter and leave the United States. U.S. dual nationals may also be required by the country of their foreign nationality to use that country’s passport to enter and leave that country. Use of the foreign passport to travel to or from a country other than the United States is not inconsistent with U.S. law.  

You can find additional information on dual nationality and the potential challenges for international travelers here.