WASHINGTON — Five years after launching the invasion of Iraq, President Bush strongly signaled Wednesday that he won't order troop withdrawals beyond those already planned because he refuses to "jeopardize the hard-fought gains" of the past year.

As anti-war activists demonstrated around downtown Washington, the president spoke at the Pentagon to mark the anniversary of a war that has cost nearly 4,000 U.S. lives and roughly $500 billion. The president's address was part of a series of events the White House planned around the anniversary and next month's report from the top U.S. figures in Iraq, Gen. David Petraeus and Ambassador Ryan Crocker. That report will be the basis for Bush's first troop-level decision in seven months.

"The battle in Iraq has been longer and harder and more costly than we anticipated," Bush said.

But, he added, before an audience of Pentagon brass, soldiers and diplomats: "The battle in Iraq is noble, it is necessary, and it is just. And with your courage, the battle in Iraq will end in victory."

Democrats took issue with Bush's stay-the-course suggestion.

"With the war in Iraq entering its sixth year, Americans are rightly concerned about how much longer our nation must continue to sacrifice our security for the sake of an Iraqi government that is unwilling or unable to secure its own future," House Speaker Nancy Pelosi, D-Calif. "Democrats will continue to push for an end to the war in Iraq and increased oversight of that war."

Bush repeatedly and directly linked the fight there to the global battle against the al Qaida terror network. And he made some of his most expansive claims of success. He said the increase of 30,000 troops that he ordered to Iraq last year has turned "the situation in Iraq around." He also said that "Iraq has become the place where Arabs joined with Americans to drive al Qaida out."

"The surge ... has opened the door to a major strategic victory in the broader war on terror," the president said. "We are witnessing the first large-scale Arab uprising against Osama bin Laden, his grim ideology, and his terror network. And the significance of this development cannot be overstated."

Bush appeared to be referring to recent cooperation by local Iraqis with the U.S. military against the group known as al-Qaida in Iraq, a mostly homegrown, though foreign-led, Sunni-based insurgency. Experts question how closely — or even whether — the group is connected to the international al-Qaida network. As for bin Laden, he is rarely heard from and is believed to be hiding in Pakistan.