Updated at 7:25 p.m.President Trump has signed a memo implementing his new policy on transgender people serving in the armed forces.A senior White House official told reporters that no transgender individuals will be allowed to join the armed services unless and until the secretary of defense and secretary of homeland security recommend otherwise.The Army, Navy, Air Force and Marine Corps are part of the Department of Defense. The Coast Guard, also covered by the new policy, is part of the Department of Homeland Security.The memo halts use of all Defense and Homeland Security resources for sex change surgery for those now serving. The only exception is for transgender service members already in treatment. This will become effective March 23, 2018, to give time for officials to develop an implementation policy.The change in policy that would have allowed transgender people to join the military had been announced by former Secretary of Defense Ash Carter but never implemented, unlike the policy change that allowed current transgender military personnel to serve openly.The policy prohibiting transgender individuals serving in the military is restored by the memo. For transgender service members already serving, the memo directs the departments of Defense and Homeland Security to determine what to do with them based on how their continued service affects military effectiveness, lethality, resources and unit cohesion.The memo calls for an implementation plan to be submitted to the president by March 23, 2018. Copyright 2017 NPR. To see more, visit http://www.npr.org/.