President Barack Obama welcomed home some of the last U.S. troops from Iraq on Wednesday, marking a symbolic end to the nearly nine-year war that strained America's armed forces and damaged its standing worldwide.

Addressing soldiers at Fort Bragg, North Carolina, home of the 82nd Airborne Division, Obama stopped short of declaring victory in Iraq but called the winding down of the conflict "an extraordinary achievement."

"It is harder to end a war than to begin one," he told about 3,000 soldiers gathered in an airplane hangar as they punctuated his speech with cheers and hollers.

Despite lingering questions about whether the United States should have invaded the Middle Eastern country, the last American troops "will cross the border out of Iraq with their heads held high," Obama said.

"Of course, Iraq is not a perfect place. But we are leaving behind a sovereign, stable and self-reliant Iraq, with a representative government that was elected by its people," he said. "We are ending a war not with a final battle, but with a final march toward home."

As of this week, there were about 5,500 U.S. troops left in Iraq, down from more than 170,000 at the height of the war that Obama's predecessor George W. Bush started in the wake of the September 11, 2001, attacks.

Michelle Obama, speaking just before her husband, injected a hint of campaign rhetoric by crediting the president for winding down the war. "He's kept his promise to responsibly bring you home from Iraq," she told the Fort Bragg soldiers.

Leaving Iraq fulfills a pledge that helped Obama win the presidency in 2008 and allows the White House to focus more on Afghanistan as well as economic worries at home, where the high jobless rate will be a major concern for voters next year.

But critics have accused Obama of ignoring warnings from U.S. and Iraqi military commanders about the dangers of a full departure by the end of this year, the timetable that Bush's advisers had laid out and the current president stuck to.

Republican contenders for the 2012 presidential race and some policy experts have said Iraq's security forces are ill-equipped to keep order in the oil-producing country and have warned new insurgent violence or upheaval could embolden Iraq's neighbor and long-time foe Iran.

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Senator John McCain, who ran against Obama for the presidency in 2008, said Obama should have convinced Baghdad to allow a small number of American troops to stay in Iraq beyond this year to help assist Iraqi security forces maintain the peace.

"It was a sad case of political expediency triumphing over military necessity, both in Baghdad and Washington," he said, calling Obama's decision to end talks about keeping some U.S. forces in Iraq represented "a failure of leadership."

Some 4,500 American troops and at least 60,000 Iraqis died in the Iraq war, which Obama has said would cost more than $1 trillion all told - a significant contributor to Washington's current fiscal strains.

The Democrat owes his White House tenure in part to his opposition to the Iraq war, which grew unpopular in the United States when military fighting morphed into sectarian violence and it became clear that Iraqi leader Saddam Hussein was not hiding weapons of mass destruction and supporting al Qaeda militants, as the Bush administration had claimed.

As an Illinois state legislator, Obama gave a stirring speech in 2002, warning that invading Iraq would plunge the United States into a "dumb war." He used his anti-war stance to distinguish himself in the Democratic presidential run-off from Hillary Cli