Published: Feb 22, 2012 12:05 PM EST

TAMPA, Fla. (AP) - Leaving nothing to chance, the U.S. military is making sure the transfer of 17 tons of shipwreck treasure to Spain later this week is handled safely. Officials at Tampa's MacDill Air Force Base said Tuesday night that they're cooperating with the Spanish government on the transfer of the of 594,000 coins and other artifacts that were wrested away from deep-sea explorers Odyssey Marine Exploration after a nearly five-year legal struggle. The company salvaged the treasure and flew it back to Tampa via Gibraltar in May 2007. At the time, it was estimated to be worth around $500 million to collectors. The treasure is believed to be from the Nuestra Senora de las Mercedes, a galleon with more than 200 people on board that was sunk in 1804 by British warships.