Brown-water navy is a term that originated in the United States Navy, referring to the small gunboats and patrol boats used in rivers, along with some of the larger ships (including converted WWII LCMs, LSTs, etc.) that supported them as "mother ships," from which they operated. A broader meaning is any naval force that has the capacity to carry out military operations in river or littoral environments, commonly known as riverine warfare. The term "brown-water" generally describes river environments carrying heavy sediment loads, such as from soil runoff or flooding. Since presence of "brown water" requires a soil source, whether riverine or coastal, the term has become associated with littoral navies.