A foreign national or alien entering the U.S. is generally required to present a passport and valid visa issued by a U.S. Consular Official, unless they are a citizen of a country eligible for the Visa Waiver Program, or are a lawful permanent resident of the U.S. or a citizen of Canada.
The Visa Waiver Program allows foreign nationals from certain countries to be admitted to the U.S. under limited conditions and for a limited time without obtaining a visa. The foreign national must arrive on an approved carrier (if coming by air or sea), staying no more than 90 days, for pleasure/medical purposes/business, and be able to prove they are not inadmissible. The foreign national is still required to have a passport.
To obtain a list of countries eligible and VWP passport requirements for the Visa Waiver Program, please visit https://www.dhs.gov/visa-waiver-program-requirements.
NOTE: All travelers transiting the United States are subject to the U.S. customs/immigration laws.
For additional information please visit https://travel.state.gov/content/visas/en.html.