He said that the United States would keep its troop level at the current 138,000 as long as necessary but that commanders were constantly reassessing needs. "If they need more troops, I will send them," pledged Mr. Bush.
In a primetime address Monday night at the U.S. Army War College, he also promised to demolish the Abu Ghraib prison that has become an ugly symbol of the U.S. occupation.
He spoke for slightly over 30 minutes. The speech came as thehas slipped to its lowest ever - down to 41 percent, with 52 percent disapproving - according to a CBS News poll.
With nearly 800 U.S. soldiers killed so far in Iraq, Bush warned that the violence would continue.
"There are difficult days ahead and the way forward may sometimes appear chaotic," he said.
In other developments:
Five months before the U.S. presidential election, Iraq has helped push down President Bush's approval rating to a new low and has increased doubts about his handling of the war.
Monday night, Mr. Bush outlined five steps he says will help Iraq achieve democracy and freedom: transferring authority to a sovereign new Iraqi government, helping establish security in areas still gripped by chaos, urging broader international support, reconstructing the country and setting up national elections.
"Completing the five steps to Iraqi elected self-government will not be easy," said Mr. Bush. "There is likely to be violence before the transfer of sovereignty and after the transfer of sovereignty."
He talked of the assassination this month of the president of the Iraqi Governing Council, Izzadine Saleem, and the beheading of American civilian Nicholas Berg. But he continued to express his resolve, saying, "No power of the enemy will stop Iraq's progress."
He said coalition forces and Iraqis have the same enemies — terrorists, illegal militia and loyalists of Saddam Hussein. "Working as allies, we will defend Iraq and defeat these enemies," he said.