Donald Trump has said he would send home all Syrian refugees the US accepts, if he becomes president.
The billionaire, who is the current frontrunner in the Republican race for the White House, told a New Hampshire rally: "If I win, they're going back." It marks a reversal in policy - earlier this month he told Fox News the US should take in more refugees.
A migrant crisis has gripped parts of Europe and the US has pledged to take 10,000 refugees from Syria next year.
Rival Republican candidate Jeb Bush called Trump's pledge "a horrible thing".
"The idea that you would send back refugees - when in American history has that ever happened?" the former Florida governor told NBC News. "We have to stand for certain values."