One of the subtle changes in armor warfare has been the decline in close cooperation between tanks and infantry. At the end of World War II, many U.S. tanks had a telephone on the rear of the tank, so the infantry could talk to the tank commander and coordinate operations. But as most infantry got faster armored vehicles to travel about it, there was less walking. The tankers got faster and more mobile tanks and no longer wanted to move around at the speed of walking infantry. In peacetime exercises the tanks tend to constantly leave walking infantry behind. Moreover, peacetime training safety procedures increasingly discouraged dismounted infantry from being too close to moving tanks. Poorly trained infantry walking near poorly trained tankers led to a few grunts getting run over, and no peacetime commander wants this on his record. So we now have the situation where the infantry end up accompanying tanks while in their armored vehicles and are no longer very effective at preventing a single enemy infantryman from putting an anti-tank rocket into the side or rear of a tank or APC.