The Justice Department on Monday night requested an emergency stay to a decision by the U.S. District Court for the District of Columbia that would require the Pentagon to start accepting transgender recruits on Jan. 1.

The Trump administration turned to the D.C. Circuit Court of Appeals, saying the Pentagon still will be reviewing the policy until February but needs the emergency stay now.

“Without this relief, the military will be forced to implement a significant change to its standards for the composition of the armed forces before it decides how to resolve this issue,” the government’s motion stated. “As military leadership has explained, this timetable will place extraordinary burdens on our armed forces and may harm military readiness.”

The president over the summer announced, via Twitter, a ban on transgender service members. But the directive has been challenged since in the courts, and a federal judge last month said the U.S. military must accept them starting Jan. 1.

The new policy reflects growing legal pressure on the issue and the difficult hurdles the federal government would have to cross to enforce Trump’s demand.

Fox News previously reported that potential transgender recruits still will have to overcome a lengthy and strict set of physical, medical and mental conditions that make it possible, though difficult, for them to join the armed services.

Maj. David Eastburn, a Pentagon spokesman, says the enlistment of transgender recruits will start Jan. 1 and go on amid the legal battles. The Defense Department also is studying the issue.

Eastburn told The Associated Press on Monday that the new guidelines mean the Pentagon can disqualify potential recruits with gender dysphoria, a history of medical treatments associated with gender transition and those who underwent reconstruction. But such recruits are allowed in if a medical provider certifies they’ve been clinically stable in the preferred sex for 18 months and are free of significant distress or impairment in social, occupational or other important areas.

Transgender individuals receiving hormone therapy also must be stable on their medication for 18 months.

The requirements make it challenging for a transgender recruit to pass. But they mirror concerns President Barack Obama’s administration laid out when the Pentagon initially lifted its ban on transgender service last year.

“Due to the complexity of this new medical standard, trained medical officers will perform a medical prescreen of transgender applicants for military service who otherwise meet all applicable applicant standards,” Eastburn said.

Aaron Belkin, director of the California-based Palm Center, an independent institute that has conducted research on sexual minorities in the military, said the 18-month timeline is fair.

“It’s a good standard because the Pentagon is treating gender dysphoria according to the same standards that are applied to all medical conditions,” he said.

However, Elaine Donnelly, president for the Center For Military Readiness, said Trump “has every right to review, revise, or repeal his predecessor’s military transgender policies, which would detract from mission readiness and combat lethality.” Court judges, she said, are not qualified to run the military.

Fox News' Jake Gibson and The Associated Press contributed to this report.