The White House is expected to send guidance to the Pentagon in coming days on how to implement a new administration ban on transgender people in the military, The Wall Street Journal reported Wednesday.

Under the policy, Defense Secretary James Mattis can consider a service member's ability to deploy as the primary legal test for deciding whether to discharge them from the military.

The White House memo also directs the Pentagon to deny admittance to transgender individuals and to stop spending on medical treatment regimens for those currently serving, according to U.S. officials familiar with the document.

Mattis also will have six months to implement the new ban — and the memo defines "deployability" as the ability to serve in a war zone, participate in exercises or live for months on a ship, the officials said.

President Donald Trump announced the transgender ban July 26 via Twitter — and Pentagon officials have been waiting for guidance since the posts first appeared.

Trump effectively reinstated a ban on open transgender service that had been lifted last year by former President Barack Obama.

Obama's move also provided for medical care for what is known as gender dysphoria.

The "deployability" issue is was immediately slammed by transgender advocates.

"Transgender people are just as deployable as other service members," Sue Fulton, the former president of Sparta, a military organization for LGBT people, told the newspaper.

"Other service members may undergo procedures when they are at home base, just as other service members schedule shoulder surgery or gall-bladder surgery."

Fulton added there were no "ongoing treatments" for transgender service members that would render them nondeployable.

"Thus, there's no difference between the deployability of transgender service members" and others, she told the Journal.

Estimates of how many transgender service members are openly serving range from 1,320 to 6,600, according to a Rand Corp. study commissioned last year by the Pentagon, the Journal reported.

Not all of them seek treatment for gender dysphoria, however, the study said.

Advocacy groups have said that as many 7,000 transgender service members are on active duty, with a total of 11,000 in the nation's armed forces.

But the Rand study added that only a small number of transgender personnel would require surgery that would prevent them from deploying.

According to the Journal, gender dysphoria is recognized as a condition requiring medical treatment by many professional associations.

For instance, the American Psychiatric Association recognizes gender dysphoria as a medical issue.

When diagnosed by a medical professional, transition therapy and reassignment surgery is considered by some insurers and states as a medically necessary treatment, the Journal reported.

The Rand report also concluded that treating transgender service members would cost between $2.4 million and $8.4 million a year.

Total military healthcare expenditures were $6.27 billion in 2014, the Journal reported.