A new policy memo from President Donald Trump concerning transgender service members may allow some to serve, but keep in place tight restrictions for many.

The White House memo, released late Friday night, highlights recommendations from Defense Secretary Jim Mattis that individuals with a history or diagnosis of gender dysphoria be barred from serving, saying these people "may require substantial medical treatment, including medications and surgery."

With limited exceptions that are not spelled out in the memo, these people will be disqualified from military service, according to the policy.

"On the advice of ... experts, the Secretary of Defense and the Secretary of Homeland Security [Kirstjen Nielsen] have concluded that the accession or retention of individuals with a history or diagnosis of gender dysphoria -- those who may require substantial medical treatment, including through medical drugs or surgery -- presents considerable risk to military effectiveness and lethality," the White House said in a released statement.

The new policy, the statement continued, would allow the military to apply health standards equally to all who serve.

Earlier Friday, Mattis' full memo was made public in a filing by the U.S. Department of Justice in U.S. District Court in Seattle. In the three-page memo, Mattis also recommends that transgender persons who "require or have undergone" gender transition be disqualified.

Those with a history or diagnosis of gender dysphoria should be allowed to serve, he said, only if they have been "stable" in their biological sex for 36 months prior to entering the military or if they receive a diagnosis while currently serving but do not require a change of gender and remain deployable.

Currently serving troops who have been diagnosed since policies created to enable transgender service were introduced under Carter may continue to serve in their preferred gender and receive appropriate treatment, Mattis said.

Gender dysphoria is defined as a conflict between an individual's biological or assigned gender and the gender with which they identify.

In his memo, Mattis called those with gender dysphoria a "subset" of transgender people who experience "discomfort" with their born sex, "resulting in significant distress or difficulty functioning."

"I firmly believe that compelling behavioral health reasons require the Department to proceed with caution before compounding the significant challenges inherent in treating gender dysphoria with the unique, highly stressful circumstances of military training and combat operations," Mattis wrote.

The White House memo comes about eight months after Trump first announced, in a series of tweets, that he intended to ban transgender people from serving in the military "in any capacity."

Those tweets caught the Pentagon off-guard; only a year before, then-Defense Secretary Ash Carter had announced a new policy allowing transgender individuals to serve openly. He ordered each of the military services to develop guidance and policies governing transgender personnel, including gender transition procedures and medical treatment.

Mattis' findings come to light as a result of the court system entering the fray in the wake of Trump's tweets. Four courts have now filed injunctions prohibiting new Pentagon policies on transgender personnel as four separate lawsuits against Trump move through the system.

The U.S. District Court in Seattle, which is adjudicating one of the lawsuits, had ordered the White House to turn over meeting documentation having to do with experts brought in to consult as Pentagon brass and the White House crafted the military transgender policy.

It's not clear how many of the estimated between 3,000 and 15,000 serving troops who identify as transgender would be considered to have a gender dysphoria diagnosis, but the policy is expected to bar most troops.

"The Secretary of Defense, and the Secretary of Homeland Security, with respect to the U.S. Coast Guard, may exercise their authority to implement any appropriate policies concerning military service by transgender individuals," Trump's memo concludes.

The specific mention of the Coast Guard is notable. Coast Guard Commandant Adm. Paul Zukunft was the first of the military service chiefs to publicly state support for transgender troops in uniform.

In August 2017, days after Trump's tweets, Zukunft told an audience at the Center for Strategic and International Studies that his office had reached out to all the openly serving transgender Coast Guardsmen to say the service did not plan to "break faith" with them.

In a December interview, Zukunft told Military.com he had determined that a tweet did not constitute an executive order, and thus felt empowered to make his statement. At the time, Zukunft said a lot of progress had been made on the topic and the services were now moving forward "in lockstep" to craft policy on transgender troops.

The Palm Center, a think tank on LGBT issues in the armed forces, denounced Trump's policy Friday night in a brief statement.

"Today's announcement fulfills President Trump's July 2017 tweet calling for the reinstatement of the transgender military ban," Palm Center Director Aaron Belkin wrote. "In service to the ideological goals of the Trump-Pence base, the Pentagon has distorted the science on transgender health to prop up irrational and legally untenable discrimination that will erode military readiness. There is no evidence to support a policy that bars from military service patriotic Americans who are medically fit and able to deploy. Our troops and our nation deserve better."

-- Hope Hodge Seck can be reached at hope.seck@military.com. Follow her on Twitter at @HopeSeck.