Donald Trump says he didn't suggest creating a database to track Muslims in America, but instead was answering a question from a reporter about the idea.

In a tweet sent Friday, the Republican presidential front-runner adds that "we must defeat Islamic terrorism" and "have surveillance, including a watch list, to protect America."

On Thursday, Trump told a reporter from NBC News that he would "certainly implement" a database to track Muslims living in the U.S.

He said Muslims would be signed up at "different places" and added, "It's all about management."

Asked whether registering would be mandatory, Trump responded: "They have to be."

Trump's rival Republican presidential candidates condemned the database idea on Friday, with former Florida Gov. Jeb Bush calling it "abhorrent."