The United States Coast Guard (USCG) is a branch of the United States Armed Forces responsible for enforcing maritime law, protecting the environment, and providing search and rescue operations. An ENS (Ensign) is a junior officer rank in the USCG, typically held by recent graduates of the USCG Academy or Officer Candidate School. A CMDR (Commander) is a senior officer rank in the USCG, typically held by officers with several years of experience.