The U.S. military is moving more than 4,000 Marines and sailors to waters surrounding Latin America and the Caribbean as part of an expanded mission to deter and, if ordered, confront regional drug cartels, two Defense officials told CNN. The shift marks one of the largest recent troop surges to the hemisphere and is intended to broaden the president’s military options against narcotics networks classified as threats to U.S. national security. The deployment centers on the USS Iwo Jima Amphibious Ready Group and the 22nd Marine Expeditionary Unit, which are being reassigned to U.S. Southern Command after a three-week repositioning of forces. Additional assets include a nuclear-powered attack submarine, extra P-8 Poseidon reconnaissance aircraft, several destroyers and a guided-missile cruiser, according to the officials. The contingent is expected to remain under SOUTHCOM’s control for at least several months. Pentagon sources described the buildup as a show of force rather than an immediate precursor to precision strikes, though it gives commanders and President Donald Trump a wide range of contingencies should direct action be ordered. A Marine spokesperson said the MEU “stands ready to execute lawful orders and support combatant commanders as requested.” Some defense officials expressed concern that Marine units lack specialized training in drug-interdiction operations and would have to rely heavily on the Coast Guard if tasked with seizures at sea. The maritime reinforcement follows a March deployment of destroyers near the U.S.–Mexico border and aligns with a memorandum from Defense Secretary Pete Hegseth directing the Pentagon to prioritize homeland defense, curb narcotics trafficking and secure strategic corridors such as the Panama Canal.