Domestic Terrorism Prevention Act of 2018 This bill authorizes: (1) a Domestic Terrorism Unit within the Office of Intelligence and Analysis of the Department of Homeland Security (DHS), which shall be responsible for monitoring and analyzing domestic terrorism activity; (2) a Domestic Terrorism Office in the Counterterrorism Section of the National Security Division of the Department of Justice (DOJ), which shall be responsible for investigating and prosecuting incidents of domestic terrorism; and (3) a Domestic Terrorism Section within the Counterterrorism Division of the Federal Bureau of Investigation (FBI), which shall be responsible for investigating domestic terrorism activity. Such offices shall focus on the most significant domestic terrorism threats, as determined by the number of domestic terrorism related incidents in the preceding year. DHS, DOJ, and the FBI shall annually submit to Congress a joint report authored by such offices, which shall include: an assessment of the domestic terrorism threat posed by White supremacists; an analysis of incidents or attempted incidents of domestic terrorism that have occurred in the United States since April 19, 1995, for the first report, and during the preceding year, for each subsequent report; and a quantitative analysis of domestic terrorism for the preceding year. The bill also authorizes a Domestic Terrorism Executive Committee, which shall coordinate with key public safety officials to promote information sharing and ensure an effective joint effort to combat domestic terrorism. The State and Local Anti-Terrorism Program, funded by DOJ's Bureau of Justice Assistance, shall include training and resources to assist state, local, and tribal law enforcement officers in understanding, detecting, deterring, and investigating acts of domestic terrorism. The joint terrorism task forces of the FBI and state, local, and regional fusion centers shall each, in coordination with the committee and such offices: (1) share intelligence to address domestic terrorism activities; (2) conduct an annual, intelligence-based assessment of domestic terrorism activities in their jurisdictions; and (3) formulate and execute a plan to address and combat such activities.