(CNN) The Pentagon said it will begin processing transgender applicants to the military on January 1 after a federal judge declined on Monday to put the deadline on hold.

Transgender service members are challenging President Donald Trump's memorandum directing the secretary of defense to bar transgender Americans from military service. The challengers have so far been successful in blocking the President's policy from going into effect while the lawsuit plays out in court. Their latest victory came Monday, when Judge Colleen Kollar-Kotelly ruled that the government would not be "irreparably injured" if the January 1 deadline remained in place as the lawsuit continues.

After the ruling, however, the Justice Department appealed the judge's ruling to a DC-based federal appeals court.

"The government seeks a stay pending appeal of the portion of the injunction concerning accessions," government lawyers said in their brief filed late Monday. They argued that implementing "a significant change" to military standards for the composition of the armed forces even before a court decides the merits of the case would "place extraordinary burdens on our armed forces and may harm military readiness."

Justice Department spokeswoman Lauren Ehrsam said in a written statement: "Plaintiffs' lawsuit challenging military service requirements is premature for many reasons, including that the Defense Department is actively reviewing such service requirements, as the President ordered, and because none of the Plaintiffs have established that they will be impacted by current policies on military service."

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