He's 5.6 and I have a feeling that this is a particular phase. Mercifully he's showing no inclination to hit other DC, just me when I tell him he can't have/can't do something he wants. I've done the speaking to him firmly about it, and if it's feasible at the time he loses TV/computer use for the night, but that's not alwas an available sanction. I'd rather not use a smack as a punishment for physical aggression as I think that's thoroughly illogical - any other tips?