Another argument against this approach is that North American oil sources aren't as easily extracted as Middle Eastern sources. Part of the transition to North American sources includes developing better extraction technology as these sources start to be exploited. That requires real experience and years of R&D. If we just ignored our sources until we became 100% dependent on them, we're not going to be able to extract them quickly enough or efficiently enough. We've got to build up the technology and infrastructure before we become dependent.