It is widely believed, and I think established by White House recordings, that Nixon established the War on Drugs to attack people he didn't like: Hippies and blacks.

I believe that in public affairs and politics, the way to evaluate and act is to look at the (expected) outcomes and to ignore all the rhetoric. First, the outcomes are what matters and there's not a high correlation with the claims made ahead of time. Second, politicians are sophisticated enough to know what the outcomes will be; I think it's reasonable to assume that they know what is going to happen.