The US government’s latest move in its crackdown on immigration is to target US citizens.

US Citizenship and Immigration Services is setting up a new office and hiring dozens of lawyers to track down people who may have lied on their citizenship applications, the AP reports. People who are found to have lied could be “denaturalized,” or stripped of their US citizenship.

These cases have been tackled in the past but only when they arose in the course of normal work. An immigrant defense lawyer told the AP that the Department of Justice has only prosecuted 305 such cases since 1990.

USCIS director L. Francis Cissna said he there were potentially “a few thousand” cases where people had submitted fraudulent citizenship applications. He wouldn’t tell the AP how much the new office would cost, but said it would come out of the regular USCIS budget, which is funded by immigration applications.

USCIS did not immediately comment on how this would affect other departments or visa and citizenship processing times. We will update if they do.