WASHINGTON – Barack Obama's promise Thursday to work to “end our dependence” on Middle East oil within a decade may be good political rhetoric when Americans have been paying $4 a gallon at the gas pumps, but the goal likely would be difficult – perhaps impossible – to achieve and flies in the face of how global oil markets work.

Last year, the United States imported about 10 million barrels of oil a day, of which about 20 percent came from the Persian Gulf states – principally Saudi Arabia, which sent 1.4 million barrels a day of crude to the United States.

Even if U.S. oil demand were to decline significantly over the next decade with more fuel-efficient automobiles and a greater use of biofuels such as ethanol, the United States, which domestically pumps 5.6 million barrels of oil a day, will continue to rely heavily on imports for decades to come, most energy experts acknowledge, with little regard to where the oil comes from.

The United States uses about 21 million barrels of oil products a day. Even if the United States cuts oil demand by about 10 percent, equivalent to Persian Gulf oil imports, it is likely to continue to rely on oil imports and make no distinction as to where it is pumped, energy experts say.

“The United States is now more dependent on foreign oil than it ever was,” Amy Myers Jaffe, an energy expert at Rice University, told a congressional hearing earlier this year, adding the U.S. now imports about 60 percent of its oil, compared to 35 percent in 1973 at the time of the Arab oil embargo.

And over the next dozen years, the United States may become increasingly dependent on Persian Gulf supplies, said Jaffe, predicting a doubling of imports from the Persian Gulf by 2020.

Ironically, President Bush in 2007 established a similar goal, dubbed the “10-in-20” energy plan in which he called for increased use of biofuels and development of more fuel efficient cars and trucks to end U.S. dependence on Persian Gulf oil.

Later, the White House explained that the plan did not envision ending Persian Gulf oil imports directly, but only that it would reduce U.S. oil demand equivalent to roughly the amount of oil supplied by the Persian gulf producers.

Obama's pledge to cut dependents on foreign oil is a key element of his overall energy policy, which envisions aggressive development of alternative fuels and technologies to improve energy efficiency.

“For the sake of our economy, our security, and the future of our planet, I will set a goal as president: In 10 years, we will finally end our dependence on oil from the Middle East,” Obama declared in his presidential acceptance speech to the Democratic convention in Denver.

Among the top 15 oil exporters to the United States, three are from Persian Gulf: Saudi Arabia, Iraq and Kuwait. Saudi Arabia is the overall No. 2 oil exporter to the United States at 1.5 million barrels a day, exceeded only by Canada. Iraq exported 583,000 barrels a day and Kuwait 219,000 barrels a day during the first six months of the year, according to the federal Energy Information Administration.

The United States does not import oil directly from Iran, but some of its oil may eventually end up in the United States, anyway, because of the global nature of the oil markets.