What is the main reason for inspecting an alien upon arrival?

Inspecting an alien upon arrival primarily serves to determine the purpose of their visit. This process is crucial because it helps immigration officials assess whether the individual is entering the country legally and for legitimate reasons, such as tourism, work, study, or family reunion. Understanding the purpose of a visitor's entry is fundamental to upholding the country’s immigration laws and policies and ensuring that visitors comply with the conditions of their visa or entry permit.

Assessing the purpose also allows border control to make informed decisions about potential risks associated with the visitor, such as immigration violations or security threats. This is an essential step in maintaining national security and ensuring that the immigration system operates effectively.