By John Whitesides and Amanda Becker
DES MOINES, Iowa (Reuters) - U.S. Democratic presidential front-runner Hillary Clinton played defense over her 2003 vote backing the U.S. invasion of Iraq and inched away from President Barack Obama on Syria and the rise of Islamic State militants during a contentious debate on Saturday.
Clinton's rivals for the White House, Bernie Sanders and Martin O'Malley, took a more aggressive tone than in their first debate last month. They accused Clinton of being too cozy with Wall Street and taking campaign donations that made her unwilling to stand up to corporate interests.
The day after a series of bomb and gun attacks that killed at least 129 people in Paris, Sanders linked Clinton's U.S. Senate vote authorizing the Iraq invasion to the regional chaos that followed. Sanders called it "one of the worst foreign policy blunders in the modern history of the United States."
"I would argue that the disastrous invasion of Iraq, something that I strongly opposed, unraveled the region immensely, and led to the rise of Al Qaeda and to ISIS," said Sanders, a U.S. senator from Vermont.
"I don't think any sensible person would disagree that the invasion of Iraq led to the massive level of instability we are seeing right now," he said.
Clinton, who has frequently called the Iraq vote a mistake, said it should be placed in the historical context of years of terrorism before the invasion.
"This is an incredibly complicated region of the world. It's become more complicated. And many of the fights that are going on are not ones that the United States has either started or have a role in," she said.
Clinton said countries in the region would have to play a major role in resolving the conflict. "It cannot be an American fight. And I think what the president has consistently said, which I agree with, is that we will support those who take the fight to ISIS," she said.
Clinton struck a sharp contrast to Obama's comments in an interview aired on Friday that ISIS had been contained, saying it "cannot be contained, it must be defeated."
'FILLING THE VACUUM'
She also played up her efforts to find solutions in the region, noting she had pushed for an effort to train and equip Syrian moderates "because I thought there would be extremist groups filling the vacuum."
The former secretary of state drew another contrast with Obama on Syrian refugees, saying she urged the administration to increase its plan to accept 10,000 refugees in fiscal 2016.
"I said we should go to 65 (thousand), but only if we have as carefully screening and vetting process as we can imagine, whatever resources it takes," she said.
Republican presidential contenders have criticized Obama for what they say was an inadequate response to the rise of Islamic State in Iraq and Syria, and called on the administration to reconsider plans to allow thousands of Syrian refugees to be resettled in the United States.
The second debate for Democrats seeking their party's nomination for the November 2016 presidential election focused heavily on foreign policy and ways to combat terrorism after the Paris attacks.
The candidates and audience at Drake University in Des Moines, Iowa, observed a moment of silence at the beginning of the debate to honor those killed in France.
Clinton has always been from the more hawkish wing of the Democratic Party. Her support for the 2003 Iraq invasion played a major role in her primary loss to Obama in the 2008 White House race.
The foreign policy focus was a dramatic shift in emphasis in a Democratic presidential race that so far has been dominated by domestic economic issues such as income inequality, college affordability and family leave.
The Democrats returned to that theme later in the debate. Sanders criticized Clinton for taking Wall Street donations and noted her opposition to reinstating the Glass-Steagall Act, the 1933 law that established a firewall between investment and commercial banking. Its removal has been blamed by some for helping lead to the 2008 financial crisis.
"Over her political career, Wall Street has been a major, the major donor to Hillary Clinton. Now maybe they're dumb, but I don't think so," said Sanders, who favors reinstatement of the act.
Clinton accused Sanders of impugning her integrity and said reinstating the law was not enough to rein in corporate influence and reform Wall Street.
"Reinstating Glass-Steagall is a part of what very well could help, but it is nowhere near enough," she said. "I just don't think it would get the job done, I'm all about making sure it actually gets results for whatever we do."
With the political clock ticking to the first nominating contest in Iowa on Feb. 1, Clinton has opened a commanding lead over Sanders, her prime challenger, in national and Iowa polls. O'Malley, former governor of Maryland, trails well behind, in single digits in most polls.