Nowadays no first-world country is capable of being fully self-sustaining without suffering immensely - especially the US, which relies heavily on cheap energy with large amounts being imported.
While I agree with your point about self-sustainability, the US now produces almost as much energy as it uses. From the world bank (http://data.worldbank.org/indicator/EG.IMP.CONS.ZS) these are 2013 figures percent of energy use imported:
Denmark 4
France 46
Germany 62
Italy 77
Netherlands 10
Spain 71
Sweden 29
Japan 94
Korea 83
US 15
Canada -73
Mexico -19