On November 13, 2001, shortly after the September 11 terrorist attacks, President George W. Bush announced that the SPR would be filled, saying, "The Strategic Petroleum Reserve is an important element of our Nation's energy security. To maximize long-term protection against oil supply disruptions, I am directing the Secretary of Energy to fill the SPR up to its capacity." The highest prior level was reached in 1994 with . At the time of President Bush's directive, the SPR contained about . Since the directive in 2001, the capacity of the SPR has increased by due to natural enlargement of the salt caverns in which the reserves are stored. The Energy Policy Act of 2005 has since directed the Secretary of Energy to fill the SPR to the full authorized capacity, a process which will require a physical expansion of the Reserve's facilities.