KEEENE, N.H. -- Republican presidential front-runner Donald Trump says he would send back Syrian refugees taken in by the U.S. if he's elected president.

Trump said during a rally in New Hampshire Wednesday that he's worried the refugees could be disguised Islamic State militants.

He says that if he wins, the refugees are "going back."

Millions of Syrians, many risking their lives, have been fleeing a civil war that has killed more than 250,000 people since March 2011.

But Trump questioned why Syrians were fleeing their country instead of staying and fighting.

Secretary of State John Kerry announced earlier this month that the U.S. would significantly increase the number of migrants it takes in over the next two years.