MADRID (AP).- Spain said Monday it will soon send hulking military transport planes to Florida to retrieve 17 tons of treasure that U.S. undersea explorers found but ultimately lost in American courts, a find experts have speculated could be the richest shipwreck treasure in history. The Civil Guard said agents would leave within hours to take possession of the booty, worth an estimated euro380 million ($504 million), and two Spanish Hercules transport planes will bring it back. But it was not exactly clear when — Monday or Tuesday — the planes and the agents would leave Spain. Last week, a federal judge ordered Tampa-based Odyssey Marine Exploration to give Spanish officials access to the silver coins and other artifacts beginning Tuesday. Odyssey found them in a Spanish galleon, the Nuestra Senora de las Mercedes, in 2007 off Portugal. Spain argued successfully in court