A main supply route (MSR) [1] is the route or routes designated within an area of operations upon which the bulk of traffic flows in support of military operations [2] and humanitarian operations. [3] [4] MSR is a term that is also used in insurgency and irregular war scenarios. [5]
Because of the intense and predictable flow of constrained military traffic MSRs can often become targets for opposing forces, as was the case with the Airport Road in Baghdad, a short but dangerous route. [6]