Update, 11/20/2015, 11:17 a.m.: On Thursday night between campaign town hall events, Donald Trump doubled down on his suggestion that Muslim citizens should be logged in a database and required to carry special identification. When asked, Trump responded that he would “certainly implement” the database system, but that “there should be a lot of systems, beyond databases.” An NBC News reporter also asked what the difference was between Trump’s proposed idea and requiring Jews to register in Germany during Nazi rule, to which Trump repeatedly replied, “You tell me,” before continuing to sign autographs.

Amid growing concern following last week’s terrorist attacks in Paris, including calls from 30 governors to halt the relocation of Syrian refugees, Republican front-runner Donald Trump has taken things a step further.

In an interview with Yahoo, Trump explained that the United States would have to implement new and draconian strategies to protect the homeland.

“We’re going to have to do things that we never did before,” he said. “And some people are going to be upset about it, but I think that now everybody is feeling that security is going to rule. 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.”

What type of unthinkable things is Trump—who has also floated the idea of shuttering certain mosques—proposing? He says he’s potentially open to the creation of a database to track Muslim citizens, or requiring that Muslim Americans carry a special form of identification noting their faith.

It is worth pointing out that of the 745,000 refugees resettled in the United States since the September 11 terrorist attacks, only two have been arrested on terrorism-related charges, and in that case they were allegedly trying to aid Al Qaeda in Iraq.