Republican presidential candidate Donald Trump answers a question during a news conference before a campaign rally in Worcester, Mass., on Wednesday. (Reuters/Brian Snyder)

Republican presidential candidate Donald Trump, who has called for expanded surveillance of American Muslims, is refusing to rule out extreme measures that include warrantless searches or faith-based identification requirements.

"We're going to have to do things that we never did before. Some people are going to be upset about it, but I think that now everybody is feeling that security is going to rule,” Trump told Yahoo News in an interview published Thursday. “And certain things will be done that we never thought would happen in this country in terms of information and learning about the enemy. And so we’re going to have to do certain things that were frankly unthinkable a year ago.”

When pressed on whether these measures might include tracking Muslim Americans in a database or noting their religious affiliations on identification cards, Trump would not go into detail -- but did not reject the options.

“We’re going to have to — we’re going to have to look at a lot of things very closely,” Trump said. “We’re going to have to look at the mosques. We’re going to have to look very, very carefully.”

The businessman has escalated his rhetoric on national security issues since the terrorist attack last week in Paris. On Monday, Trump told MSNBC that he would not rule out monitoring mosques in the United States and potentially closing them.

"Well, I would hate to do it, but it's something that you're going to have to strongly consider because some of the ideas and some of the hatred — the absolute hatred — is coming from these areas," he said.

Trump has also become a vocal critic of the Obama administration's plan to expand the number of Syrian refugees the United States will bring into the country. Trump has repeatedly stated that the administration wants to expand the number to as many as 250,000 Syrian refugees – though the administration has proposed bringing up to 10,000 in the coming year. Those refugees are subject to a years-long screening process before they are allowed to enter the country.

Trump has instead called for creating a “safe zone” in Syria to protect those fleeing the conflict: “What I like is: build a safe zone in Syria. Build a big, beautiful safe zone. And you have whatever it is so people can live, and they’ll be happier," Trump told a crowd in Knoxville, Tenn., Monday. “It’ll cost you tremendously much less, much less, and they’ll be there and the weather’s the same."

The Trump campaign did not immediately return a request for details on such plans, including whether his proposals would require the creation of a special agency.