During the First and Second World Wars, hundreds of thousands of naval mines were laid by military forces in the Baltic Sea, and in waters around the world. It was a tool to cripple shipping and hinder ship movement in order to gain a strategic advantage in the conflicts. This, combined with aerial bombardment and naval gunfire, resulted in tens of thousands of potentially dangerous pieces on unexploded ordnance (UXO) being left off the busy shores of the three Baltic nations – Latvia, Lithuania, and Estonia. These relics of war still pose a risk to commercial shipping and fishing.