U.S. Army combat engineers use bridge erection boats to place a ribbon float bridge across the Arkansas River during field training near Fort Chaffee, Ark., in July. Ribbon bridges like this will be used by the Army's 1st Armored Division to cross the Sava River between Croatia and Bosnia and Herzegovina. The engineers are part of the NATO Enabling Force of Operation Joint Endeavor. Enabling forces are moving into the Croatia, Bosnia and Herzegovina, and Slovenia theaters of operation to prepare entry points for the main Implementation Force.