From attempts to fool the other team by Dressing as the Enemy and the potential of friendly fire on markerless modes to the fact that the majority of these vehicles are premium vehicles ( Bribing Your Way to Victory for some), they're quite controversial. For example, the P-47D from the US tree is available for both the Germans and the Soviets, the Germans have access to Soviet T-34s and the Japanese can use German Bf 109 E-7s and American F4U Corsairs. Some vehicles from other nations are available in the tech trees, as either captured vehicles from enemy nations or lend-lease vehicles from allies.