Nonimmigrant Visas (NIV)
Nonimmigrant visas (also referred to as tourist or visitor visas) are required for all citizens of countries not under the Visa Waiver Program who intend to enter the United States temporarily for business, tourism, or study. Nonimmigrant visas are for temporary stays in the U.S. only and cannot be used to enter the U.S. to seek a long term or permanent stay.
To apply for a nonimmigrant visa, click here
You should apply for a visa at least 4-5 weeks before you intend to travel. Visa appointment wait times and processing vary, especially during peak travel seasons. Nonimmigrant visas for Cambodian citizens are generally valid for three months, so you should apply for a visa within three months of your departure date.