The U.S. Navy's investigation, made public on March 28, concluded that the ship's powder magazines were ignited when an external explosion was set off under the ship's hull. This report poured fuel on popular indignation in the US, making the war inevitable. Spain's investigation came to the opposite conclusion: the explosion originated within the ship. Other investigations in later years came to various contradictory conclusions, but had no bearing on the coming of the war. In 1974, Admiral Hyman George Rickover had his staff look at the documents and decided there was an internal explosion. A study commissioned by "National Geographic" magazine in 1999, using AME computer modeling, stated that a mine could have caused the explosion, but no definitive evidence was found.