War on the Rocks – In March, the South Atlantic witnessed an unusual scene: a U.S. ship turning around and sailing for home, having been refused docking rights and services by the Argentine Ministry of Foreign Affairs. From January to March, the U.S. Coast Guard deployed one of its newest cutters, the USCGC Stone, to the South Atlantic, with the mission to strengthen maritime security relations and help curb illegal fishing — predominately Chinese — off the South American coast. This was the Coast Guard’s first such regional deployment in over a decade, and its first three-quarters were a success, training and cooperating with the maritime forces of Guyana, Brazil, and Uruguay. In Argentina, however, the mission hit a snag when the government refused to provide the dock services that are routine for such a visit.The press paid little attention to this kerfuffle, but it was yet another sign that a tectonic shift is underway. In the South Atlantic, former U.S. security partners are building stronger ties with China, a shift that presents critical future risks for Washington and the inter-American community.