The two candidates differed sharply on the issue of policy towards Muslims during the second US presidential debate, with Hillary Clinton accusing Donald Trump of giving a "gift to ISIS" by suggesting Muslims be banned from entering the United States.
Mr Trump's proposal for a ban on Muslims from entering the US has modified in recent months to one in which people from Muslim-majority countries would be subject to what he calls "extreme vetting".
Mr Trump attacked Mrs Clinton and US President Barack Obama for refusing to use the term "radical Islamic terror".
"Now to solve a problem you have to be able to state what the problem is or at least say the name. She won't say the name and President Obama won't say the name. But the name is there, it's radical Islamic terror and before you solve it you have to say the name," he said.
Mrs Clinton said that Mr Trump's positions and proposals were giving encouragement to extremist groups.
"This is a gift to ISIS and the terrorists, violent jihadist terrorists. We are not at war with Islam, and it is a mistake and it plays into the hands of the terrorists to act as though we are," said Mrs Clinton.
Pressed by moderator Martha Raddatz on whether he still supports a ban on Muslims, Mr Trump was evasive, saying, turning the focus instead to Mrs Clinton, who he said wants to allow refugees who may be hostile to the US to flood into the country.
Mrs Clinton said Mr Trump's proposal to ban Muslim immigrants would cause great distress within the US and it was "unwise and dangerous".
She said what Mr Trump said about Muslims is being used to recruit fighters for so-called Islamic State.
Mr Trump went on to talk about criminal illegal aliens, saying that drugs are pouring through the southern US border.
He said he is "going to force them right back into their country".
