Department of Homeland Security and U.S. Customs and Immigration Services employees will no longer be able to process applications that contain an "X’ marker for gender.

A letter to DHS field operations and USCIS employees obtained by Fox News Digital advises officials to "not make a final decision on any application that would produce a document with an "X" marker, citing President Donald Trump’s January 20 executive order that "prohibits using the ‘X’ marker on our documentation and in our systems."

"This is consistent with President Trump’s executive order that the U.S. recognizes two sexes, male and female," DHS Assistant Secretary for Public Affairs Tricia McLaughlin told Fox News Digital. "This is common sense."

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The letter comes after Trump signed an executive order on his first day in office aimed at shifting the language used by the federal government in documentation, including a move to replace the term "gender" with "sex" on official documents.

"The erasure of sex in language and policy has a corrosive impact not just on women but on the validity of the entire American system. Basing Federal policy on truth is critical to scientific inquiry, public safety, morale, and trust in government itself," the order signed by Trump states.

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The move also reverses changes made during the Biden administration, including giving Americans who do not identify with either of the two biological sexes the option to mark documents such as passports with an "X" instead of "male" or "female."

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But Trump’s order calls for all federal agencies to ensure that all documents "accurately reflect the holder’s sex," which the order defines as "an individual’s immutable biological classification."