The Battle of the Philippine Sea was fought 19-20 June 1944 in the waters west of the Mariana Islands by elements of the Imperial Japanese Navy's Combined Fleet and of the United States Navy's Pacific Fleet. The battle resulted from the Japanese reaction to the American invasion of the island of Saipan. Instead of attacking the troop transports off Saipan, Admiral Toyoda chose to engage the American carrier forces in what he intended to be the long-awaited “decisive battle” that would crush U.S. naval power.