The price Americans pay for imported oil covers none of the likely costs of future supply interruptions brought on by such dependence.

And it could come from the Strategic Reserve, which was created after the 1973-74 oil crisis as a defense against temporary supply interruptions.

At the "basic assurances" level, suppliers would agree to substitute for each other to cover certain supply interruptions to customers.

A strong domestic oil industry is our insurance policy against supply interruptions.

"During a real or perceived supply interruption, inventories might be husbanded because of rising price expectations," the study said.

At the same time, Exxon flatly denied suggestions that it used the temporary supply interruption to justify raising its own prices.

It is only because a supply interruption always affects price that we care about oil's uninterrupted flow.

That makes it possible to reach every point within the country without a supply interruption.

While supply interruptions have caused repeated spikes in pricing since 1990, longer range price trends respond to limitations in resources and their rates of development.

There are other contingencies at play, too: fuels, like natural gas, could experience a supply interruption that leads to enormous price spikes.