Many families do not allow young children to watch violent movies or cartoons, do not allow toy soldiers or guns into the house, and encourage their children to play games that do not involve shooting, fighting or killing. This is almost an impossible task, however. We live in a violent world that is showcased every night on the news - we are a world at war. Not only that, but many cartoons, from the invention of such things, portray violence at some level, from Wily E. Coyote trying to blow up Road Runner to the more recent Power Rangers brand of action. You can't completely shield your children from violence; virtually every child has picked up a stick and pretended it was a gun, tackled her brother in a wrestling match, or played cops and robbers. It is inevitable that children will be exposed to violence at some level; the only thing that can help your child grasp the concepts of imagination versus reality is you.
When a child plays with toy soldiers, he may not comprehend that he is playing with death. He doesn't debate the hereafter or worry about decomposition or the fact that death is permanent. He shoots a plastic army man with a plastic machine gun, finishes his battle, and sets each toy back up to be shot at again. This is the time to let him play, let him experiment with his toys without lecturing him on the metaphysical game he is imitating.
Toy soldiers allow little girls and boys to explore some of the violence they see every day without consequences, without pain. This is the time to learn about imagination and not be concerned with the realities of death. Toddlers can't understand the concept of death so there is no reason to turn play with toy soldiers into a somber introduction into life and death.
As kids get older, you can start to discuss the difference between reality and imagination by pointing out that cartoons are simply drawings and that toy soldiers cannot feel pain or die but that real soldiers do. Older kids can understand that video games and movies are not real and that those same actions in real life would have consequences.