Possible Clues:

• Org. that might answer an SOS
• Gp. patrolling shores
• SOS responder, for short
• Org. whose academy's motto in English is 'The sea yields to knowledge'
• Cutter initials
• Homeland Security dept
• Mil. branch under the Department of Homeland Security
• Maritime search-and-rescue gp
• Hurricane Katrina rescue gp
• It operates under the Dept. of Homeland Security