Biometric Identification Transnational Migration Alert Program Authorization Act of 2018 (Sec. 2) This bill amends the Homeland Security Act of 2002 to provide statutory authority for the Department of Homeland Security (DHS) Biometric Identification Transnational Migration Alert Program (BITMAP). That program was established to address and reduce national security, border security, and terrorist threats before such threats reach the international border of the United States. In carrying out BITMAP operations, U.S. Immigration and Customs Enforcement must: (1) coordinate foreign and U.S. officials to facilitate the sharing of biometric and biographic information of foreign nationals to identify and screen such nationals for terrorism and threats to national or border security; (2) provide capabilities, including training and equipment, to collect and compare biometric and biographic identification data of foreign nationals to protect against national security, border security, or terrorist threats and illegal entries; and (3) ensure that such data are incorporated into appropriate government databases. Before carrying out BITMAP operations in a foreign country, DHS must enter into an agreement with the government of such country that outlines such operations and must provide the congressional homeland security committees with a copy of the agreement.