The US Navy (USN) Oliver Hazard Perry Class Guided Missile Frigate USS SAMUEL B. ROBERTS (FFG 58) transits through the waters of Rio de Janeiro, Brazil, during UNITAS (United International Antisubmarine Warfare Exercise) 47-06 Atlantic Phase. Naval forces from Argentina, Brazil, Spain, Uruguay and the United States are participating in UNITAS 47-06 Atlantic phase. This is a US Southern Command sponsored exercise that enhances friendly, mutual cooperation and understanding between participating navies by enhancing interoperability in naval operations among the nations of the Western Hemisphere