The first American warship sunk during World War 2?

Answer 1

Some people would say the USS Panay, a gunboat bombed on the Yangtze River in China in 1937 by Japanese aircraft and sunk, about twenty miles from where the Rape of Nanking was going on. The Japanese aircraft machine gunned survivors in the water. The ship was clearly marked with large American flags on awnings stretched over its decks, and was a stationary target, tied up alongside four American-flag oil tankers. The Japanese "apologized", claimed it was "inadvertent", and paid reparations.

Others would say the USS Reuben James, (DD 245), a destroyer immortalized in a Woody Guthrie song, sunk by a German U-boat, U551, on October 31, 1941. She was an old "four-piper" WWI ship. In 1941 the US had begun escorting convoys of war materials bound for the UK as far as Iceland. Neither selling these war materials to the UK, and certainly not providing them a naval escort to the middle of the Atlantic is the act of a neutral, which the US was claiming to be at the time. The Reuben James was on the "Neutrality Patrol" duty when sunk.

Both of those were of course before the US was an official belligerent. The ships lost in Pearl Harbor (the first of which was the USS Oklahoma, which keeled over from five torpedoes, all on the port side, moments before the USS Arizona blew up) were also sunk before the US had declared war on anybody.

After the US declared war on Japan, I don't recall offhand any ship losses before the Battle of the Java Sea on February 27, 1942, which was a complete annihilation of the ABDA ships involved - American, British, Dutch and Australian.