USS St. Louis returns to patrol the southern border again

The littoral combat ship USS St. Louis (LCS 19) left Naval Station Mayport on September 13 to take over U.S. Northern Command’s mission patrolling waters near the U.S. southern border, the U.S. Navy said. The ship relieves USS Cooperstown (LCS 23), which returned to Mayport on August 31 after a four-month deployment to the region.

St. Louis previously served in the same role, completing a surge deployment that ended in November 2025. Since then, the mission has rotated among Freedom-variant littoral combat ships based at Mayport: USS Wichita (LCS 13) relieved St. Louis in November, and Cooperstown relieved Wichita in May 2026.

“Our crew has trained relentlessly for this deployment, and they stand ready for whatever challenges lie ahead,” said Cmdr. Lester Shewmake, commanding officer of USS St. Louis. “I could not be more proud to lead these Sailors.”

U.S. Northern Command is working with the Department of Homeland Security to add military support to U.S. Customs and Border Protection operations along the southern border. Navy ships assigned to the mission operate under the command’s maritime homeland defense authorities, working to interdict drug trafficking and other illegal activity at sea. Ships taking part typically carry an embarked U.S. Coast Guard Law Enforcement Detachment, which handles the actual boardings and arrests during interdictions, since Navy personnel do not have law enforcement authority on their own.

Cooperstown’s deployment, part of an effort the Navy has named Operation Ardent Vanguard, included stops at Corpus Christi, Texas, and patrols in the Gulf of America, the name the Trump administration adopted for the Gulf of Mexico in 2025. The Navy has not said whether St. Louis’s deployment will follow a similar track or how long it is expected to last.

Littoral combat ships are shallow-draft vessels built to operate close to shore, a design suited to patrolling coastal waters rather than open-ocean combat. St. Louis is the 22nd LCS delivered to the Navy and the tenth Freedom-variant ship in the class, which is built around a steel monohull, distinct from the aluminum trimaran design used on the competing Independence variant. The ship is assigned to Littoral Combat Ship Squadron 2 and homeported at Mayport, Florida.

St. Louis is the seventh Navy ship to carry the name. The first, a sloop of war launched in 1828, spent much of its service patrolling the coasts of the Americas and served as flagship of the West Indies Squadron, which worked to suppress piracy in the Caribbean and Gulf of Mexico during the 19th century.