 The Coast Guard originally created MARSEC to be compatible with, and respond in unison to the Department of Homeland Security’s (DHS) Homeland Security Advisory System (HSAS).With the introduction of the National Terrorism Advisory System (NTAS) to replace HSAS, the Commandant of the Coast Guard will adjust the MARSEC Level, if appropriate, based on any NTAS Alert issued by DHS.Under the HSAS there were three levels to the system