After reviewing the Top-Screen and other information, DHS notifies each facility by letter. Facilities that do not “present a high level of security risk” are not subject to CFATS. These facilities have no further regulatory obligation, although a material modification at the facility may prompt further inquiry and possibly require resubmission of a Top-Screen. Facilities that do “present a high level of security risk” are assigned to one of four risk tiers that require increasingly stringent levels of security – Tier 1 facilities posing the greatest risk and requiring the most stringent security, and Tier 4 facilities posing the least risk (in relative terms) and requiring less stringent security.
