Well, don't you also think then that if someone can go and defend his/her country and witness the tragedies of war at 18, that they should be able to drink at 18?
I get what you are saying though, and Christies quote is just straight up retarded, "By raising the minimum age to purchase tobacco products to 21, we are giving young people more time to develop a maturity and better understanding of how dangerous smoking can be and that it is better to not start smoking in the first place," Christie wrote.
They are citing the strain on the healthcare system that smoking causes, but it's amazing that they still won't even try and address PTSD appropriately.