The White House on Friday ordered the United States military to stop enlisting transgender people, The Guardian reported. Transgender personnel currently in the military may continue to serve, but they could be asked to serve according to their gender at birth, the Donald Trump administration said.

The memo did not elaborate on the possible exceptions, but said the secretary of defence and the secretary of homeland security “may exercise their authority to implement any appropriate policies concerning military service by transgender individuals”.

In December 2017, the Pentagon had said it would begin enlisting transgender people from January 1, after federal court orders struck down the Trump administration’s decision.

The decision comes after Secretary of Defence Jim Mattis’ recommendation to President Donald Trump. He wrote: “In my professional judgment, these policies will place the Department of Defence in the strongest position to protect the American people, to fight and win America’s wars and to ensure the survival and success of our service members around the world.”

Pentagon officials said on Friday that they would continue to comply with federal law, The New York Times reported. The Pentagon will “continue to assess and retain transgender service members,” the daily quoted an unidentified Defence Department spokesperson as saying.

The new policy must first be published in the federal register, which requires new rules to be reviewed by the public, before being enacted.

The advocates for transgender troops have criticised this change in policy. “There is no evidence to support a policy that bars from military service patriotic Americans who are medically fit and able to deploy,” Aaron Belkin, the director of the Palm Centre, told The New York Times.

The Palm Centre focuses on sexuality and the military. “Our troops and our nation deserve better,” Belkin said.