A Maritime Safety and Security Team, or MSST, is a counter-terrorism team of the United States Coast Guard established to protect local maritime assets. It is also a harbor and inshore patrol and security team that includes detecting and, if necessary, stopping or arresting submerged divers, using the Underwater Port Security System. It is the only special force that can arrest submerged divers.

The United States Coast Guard (USCG) is the maritime security, search and rescue, and law enforcement service branch of the United States Armed Forces and one of the country's eight uniformed services. The service is a maritime, military, multi-mission service unique among the United States military branches for having a maritime law enforcement mission with jurisdiction in both domestic and international waters and a federal regulatory agency mission as part of its duties. It is the largest coast guard in the world, rivaling the capabilities and size of most navies.