The term is used in contrast to the terms "green-water navy" and "blue-water navy". At one time, it was common to refer to all non-blue-water navies as "brown-water navies". Today blue-water navies are generally defined as being capable of sustained oversea deployment, preferably with aircraft carriers,[citation needed] while green-water navies are defined as those with frigates or better, operating in coastal and regional areas. Being a brown-water navy does not imply a lack of offensive capability, as many small littoral combat ships are armed with powerful anti-ship missiles.