Washington (CNN) The Trump administration is creating an office within the agency that grants US citizenship to root out fraudsters and have their citizenship taken away.

According to US Citizenship and Immigration Services, the effort involves a new office in Southern California that will review cases and then refer them to the Justice Department, which is able to pursue denaturalization proceedings against citizens. The physical office is the culmination of an effort to stand up the unit that began in January 2017.

The targets are people who have already been rejected from the US, but who create a new identity to gain citizenship afterward.

"Nobody who obtained US citizenship by deliberately assuming a false identity will be surprised to learn they are being referred to the Justice Department for removal proceedings," said USCIS spokesman Michael Bars. "USCIS screens for deliberate acts of fraud relating to the use of false identities."

In an interview with The Associated Press, USCIS Director L. Francis Cissna said the number of cases could possibly reach up to a few thousand.

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