Hillary Rodham Clinton vowed Thursday to keep American troops out of Syria, saying in a sweeping foreign policy address she would resist sending forces to fight Islamic State militants even if there were another terrorist attack within the U.S.

Offering a detailed assessment of the conflict in Syria, the Democratic presidential front-runner said America must lead the effort to fight against IS but called on Arab nations to supply much of the military force on the ground.

During a question-and-answer session, Clinton was asked if the pressure to send in U.S. ground troops to Syria would be "unstoppable" if another terrorist attack were to occur in the U.S.

"It would certainly grow, but I think it would be a mistake," she said, noting her support for sending in more U.S. special forces, empowering U.S. trainers in Iraq and the use of an air coalition in the region. "Right now we need to keep the pressure on the people on the ground and get them to change their priorities and work together."

Speaking just before her primary rival Vermont Sen. Bernie Sanders was set to address the conflict, Clinton urged Americans to overcome partisan battles and rise above personal fear to combat the threat of jihadism across the globe.

"Turning away orphans, applying a religious test, discriminating against Muslims, slamming the door on every Syrian refugee, that is just not who we are. We are better than that," she said.

Hours later, the Republican-led House ignored a veto threat from President Barack Obama and approved a bill mandating fresh barriers for Syrian and Iraqi refugees trying to enter the country. The bill passed on a 289-13 vote with enough Democratic support to override a potential veto and came despite White House officials lobbying members of their party to oppose the proposal.

While Clinton said she largely backed the president's efforts to combat Islamic State militants, she broke with the administration's focus on ousting Syrian President Bashar Assad - a position that has stood in the way of greater military cooperation between the U.S. and Russia.

Clinton reiterated her support for a no-fly zone over the northern region of the country - a step opposed by Obama - saying it would help with conditions on the ground and pressure Assad to reach a political settlement in peace talks being brokered by Secretary of State John Kerry.

"Right now we have one overriding goal as I outlined: We need to crush their territorial domain," she said. "We have to prioritize."

She urged Turkey and Saudi Arabia to redirect their attention from battling Kurdish forces and the conflict in Yemen to the fight against Islamic State militants. And she promised that her broader approach would not lessen the pressure on Iran to comply with the recently completed nuclear deal.

Clinton also urged Congress to "swiftly" pass an updated authorization to use military force against the militants.

"This is a time for American leadership. No other country can rally the world to defeat ISIS and win the generational struggle to defeat jihadism," she said. "The entire world must be part of this fight, but we must lead it."

Her emphasis on American leadership marks a shift in tone from the second Democratic debate on Saturday, where Clinton said that the battle "cannot be an American fight."

In his remarks, Sanders placed less focus on American leadership in the conflict and made no reference to whether the U.S. should accept refugees from the region. He took a subtle dig at Clinton, citing the invasion of Iraq - an operation Clinton backed as a senator - as destabilizing the entire region for decades.

"Wealthy and powerful Muslim nations in the region can no longer sit on the sidelines and expect the United States, our young men and women and our taxpayers, to do it for them," he said, adding that those nations should commit to fighting extremists together. "They have got to come up to the plate."

Clinton's remarks were in striking contrast to those of many Republicans who have advocated for a large-scale military mobilization, new measures to bar Syrian refugees from entering the country and a congressional declaration of war. Former Florida governor Jeb Bush on Wednesday called for the US to "increase our presence on the ground," saying the number of Americans sent to the region should be "in line with what our military generals recommend, not politicians."