(a)Travel authorization required. Each nonimmigrant alien intending to travel by air, sea, or land to the United States under the Visa Waiver Program (VWP) must, within the time specified in paragraph (b) of this section, receive a travel authorization, which is a positive determination of eligibility to travel to the United States under the VWP via the Electronic System for Travel Authorization (ESTA), from CBP. In order to receive a travel authorization, each nonimmigrant alien intending to travel