 Marines with restricted mobility such as vehicle operators, or a greater need for mobility such as squad leaders, were also issued M4 carbines.In July 2015, the Marine Corps approved the M4 carbine for standard issue to front-line Marines, replacing the M16A4 rifle.The rifles will be issued to support troops while the carbines go to the front-line Marines, in a reversal of the traditional roles of "rifles for the front line, carbines for the rear".