That is how many very senior people throughout history have come to justify their actions in Afghanistan, but its not necessarily true. Certainly the strategic usefulness of the country is considerably - if not totally - offset by the costs of having to try and occupy it, unless you just do what Alexander did and kill / marry everyone you can find.
Not gonna work... us modern westerners don't really believe in marriage. That just leaves the whole-sale genocide approach... which doesn't fly with popular opinion either (although some try). Maybe this empire stuff isn't an American strongpoint?