When Adm. James Stavridis takes charge of U.S. military operations in Latin America and the Caribbean in a change-of-command ceremony on Thursday, he becomes the first naval officer ever to run the Pentagon's Southern Command headquarters.

Ever since Teddy Roosevelt's Rough Riders charged San Juan Hill, operations south of the border have been mostly the domain of ground forces. . . .

Stavridis arrives in Miami and Southcom's headquarters in Doral as a four-star admiral in an ascension that analysts say reflects 21st century military trends -- from Secretary of Defense Donald Rumsfeld's resolve to shake up traditional Pentagon thinking to new challenges at Southcom since it moved to Miami from Panama a decade ago.

Peripherally, the trend also reflects a stretched Army that is focused on other military theaters, specifically in the Muslim world.

Stavridis will take over a Southcom with a diverse mission -- planning for potential instability in Cuba after Fidel Castro dies, overseeing Guantánamo's role in the war on terrorism and its related controversies and poised to renew exchanges with the military establishments of many Latin American nations, minus Cuba, at a time of increasing anti-Americanism across the region.