Actually the US has been steadily adding to the oil reserve. Perhaps they have concerns we are not aware of. This article from a couple of days ago:
U.S. oil reserve soaks up supply
WASHINGTON -- Despite precariously low oil supplies, the government has been pumping millions of barrels into its emergency reserve, which some critics charge has contributed to a surge in crude prices and kept gasoline costs high.
The Energy Department discounts the impact of the purchases, almost 11 million barrels since the beginning of May. And energy economists and analysts are divided; some say many other factors are keeping prices high.
Nevertheless, Sen. Carl Levin, D-Mich., urged Energy Secretary Spencer Abraham this week to suspend the oil shipments into the Strategic Petroleum Reserve immediately, "until the price of oil falls from its current high levels and the private sector inventories increase."
He produced figures showing that while 11 million barrels of oil were being diverted from oil markets into the SPR, commercial inventories during the same period were declining by 10 million barrels.
"This administration's actions to fill the SPR regardless of the price of oil or the amount of oil available to the commercial sector is a major reason for these high (crude) prices," wrote Levin, senior Democrat on the Senate Governmental Affairs investigations subcommittee.
Energy Department spokesman Joe Davis said both Democrats and Republicans in Congress have made clear they want the strategic reserve, now at 611 million barrels, filled to its 700-million-barrel-capacity.
"The vast majority of Americans realize that ensuring the SPR is key to our energy and national security. That's why there is bipartisan support to fill the reserve," said Davis.
Critics, who note the administration suspended shipments to the reserve last winter because of the loss of Venezuelan oil and a looming war in Iraq, questioned the timing.
Commercial U.S. oil stocks have been at uncomfortable levels all year, putting upward pressure on prices.
While stocks rebounded slightly last week because of a boost in imports, they remained 37 million barrels, or nearly 12 percent, below the five-year average and 30 million barrels below what they were at the corresponding time a year ago, according to the DOE's Energy Information Administration.
Also, oil prices have been creeping higher to more than $30 a barrel, prompting gasoline prices to increase as well.