<P> In both the naval and land campaigns of World War I, FEBAs, FLOTs and FLETs could often be identified by eye (for example, in France and Belgium, they were defined by opposing defensive trench systems). </P> <P> Typical modern conflicts are vastly different, characterised by "war amongst the people", the concept of a "Three Block War", and the presence of an asymmetric, 360 ° threat from irregular or extremist, terrorist combatants . In those cases, the front line, FEBA, FLOT and FLET are almost conceptual ideas . The term "front line" has come to refer more to any place where bullets and bombs are flying or are likely to fly . </P>

In the front line or on the front line