Ortega's forces are dredging the river as part of an Iranian-sponsored project to build a canal along the Isthmus of Nicaragua that will rival the Panama Canal.
This reinforced the Americans' desire to build and control a canal across the isthmus of Panama, so that their ships could move between the Atlantic and the Pacific without going all the way round Cape Horn (as the American battleship Oregon had to do during the war).
Fresh from constructing a sea-level canal through the flat Egyptian sand, de Lesseps was determined, without having set foot in Panama and after only the vaguest of topographical studies, that his project through the mountainous central American isthmus would also be a sea-level canal, requiring no locks to cope with changes in altitude.