"This threat is real, but so is our resolve. Americans will not cower. We will prevail. We will defend our country, and we will defeat the evil, twisted ideology of the terrorists," she said at a press conference.
"I am absolutely in favor of and have long been an advocate for tough vetting, for making sure that we don't let people into this country — and not just people who come here to settle, but we need a better visa system," Clinton said.
She added, "Let's remember what happened on 9/11. These were not refugees who got into airplanes and attacked our city and our country. So let's not get diverted and distracted by the kind of campaign rhetoric we hear coming from the other side."
Trump's campaign responded to Clinton's criticisms, saying they are "an attempt to distract from her horrible record on ISIS."
"If Clinton really wants to find the real cause of ISIS, she needs to take a long, hard look in the mirror. The decision to remove all American troops from Iraq in 2011, which was vigorously supported by Clinton, created the vacuum that led to the founding of ISIS," senior Trump communications adviser Jason Miller said in a statement.