About this Unit
COMUSNAVSO/COMFOURTHFLT, or Commander, U.S. Naval Forces Southern Command / U.S. Fourth Fleet, traces its origins to World War II, when the original Fourth Fleet was established in 1943 to counter Axis naval threats in the South Atlantic. After deactivation in 1950, the command’s mission was assumed by other naval entities until its reestablishment in 2008 to address modern security challenges in the Caribbean, Central, and South American regions. Today, COMUSNAVSO/COMFOURTHFLT conducts a range of missions including maritime security, humanitarian assistance, disaster relief, and multinational exercises to strengthen partnerships and promote regional stability. Headquartered at Naval Station Mayport, Florida, the command operates as the naval component of U.S. Southern Command (USSOUTHCOM).
Historical Facts
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Dual-Hatted Command: COMUSNAVSO (Commander, U.S. Naval Forces Southern Command) and COMFOURTHFLT (Commander, U.S. Fourth Fleet) refer to the same admiral, who serves both as the naval component commander for U.S. Southern Command (USSOUTHCOM) and as commander of the operational Fourth Fleet.
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Historic Fourth Fleet: The original U.S. Fourth Fleet was established during World War II (1943) to protect shipping in the South Atlantic from German U-boat threats and was headquartered in Brazil.
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Reactivation in 2008: The Fourth Fleet was officially re-established on July 1, 2008, after being inactive since 1950, to address contemporary security challenges in the Caribbean, Central, and South America.
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Humanitarian Operations: COMUSNAVSO/FOURTHFLT frequently leads humanitarian assistance and disaster relief missions, such as Operation Unified Response following the 2010 Haiti earthquake.
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Partnership Focus: The unit emphasizes building partnerships and interoperability with navies and maritime services of over 30 nations in the region, through exercises like UNITAS and PANAMAX.
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Anti-Narcotics Role: The command plays a key role in countering illicit trafficking, conducting joint operations to interdict illegal drugs and transnational criminal organizations in the region.
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Headquarters: COMUSNAVSO/FOURTHFLT is headquartered at Naval Station Mayport in Jacksonville, Florida.
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Symbolic Patch: The Fourth Fleet’s emblem features a blue and yellow crest with four stars, symbolizing its numerical designation and naval heritage.
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Non-Permanent Fleet: The Fourth Fleet does not have permanently assigned ships; it commands task forces made up of assets temporarily assigned from the U.S. Navy as needed for specific missions.
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Notable Exercises: The annual UNITAS exercise, led by COMUSNAVSO/FOURTHFLT, is the longest-running multinational maritime exercise in the world, first held in 1959 and involving numerous Western Hemisphere navies.
