This is the USS Iowa, the first of the largest, most powerful battleship class ever in the United States Navy, equipped with nine 16-inch (406mm) guns that could fire nuclear shells—the only American ship in history with this capability.
The Iowa’s were used in the Pacific during World War II, but [t]he aircraft carrier, its fighter and bombers, became the most powerful force at sea. The United States cancelled two of the six Iowa-class battleships before the war was over.
The Iowa battleships were also the only ships in the US Navy capable of firing nuclear shells. They gained that capability in the 1950s and, in theory, they had it until the ships’ retirement.
The shells were called W23, “an adaptation of the W19 nuclear artillery shell was developed specifically for the 16-inch (406 mm) guns” with a “estimated yield of 15 to 20 kilotons of TNT [which made the] Iowa-class battleship’s 16 in guns the world’s largest nuclear artillery.”