All individuals attempting to enter the U.S. must first demonstrate their admissibility to U.S. Customs and Border Protection ("CBP"). This applies to all foreign nationals, including those who have already been issued a visa at a U.S. Consulate abroad, as well as those who are visa-exempt.
Part of the U.S. Department of Homeland Security, CBP is the largest uniformed law enforcement agency in the United States, with 18,000 officers stationed at access points nationwide. It is the agency responsible for protecting the borders of the U.S. and, therefore, controls access to the country. CBP is responsible for protecting the nation’s 325 ports of entry and enforcing hundreds of laws designed to protect citizens and commerce. Among the laws CBP must enforce are the immigration laws of the U.S. In carrying out its immigration enforcement duties, CBP can question, investigate, and detain arriving aliens at U.S. ports of entry.