Here is the official DoD announcement by Secretary of the Department of Defense in which he unequivocally states " The department will carry out the president’s policy direction, in consultation with the Department of Homeland Security. As directed, we will develop a study and implementation plan, which will contain the steps that will promote military readiness, lethality, and unit cohesion, with due regard for budgetary constraints and consistent with applicable law. ... The implementation plan will address accessions of transgender individuals and transgender individuals currently serving in the United States military.
... In the interim, current policy with respect to currently serving members will remain in place. "
Below that I have inserted the text of the Presidential Memorandum SUBJECT: Military Service by Transgender Individuals dated August 25, 2017
BLUF accession of openly transgender individuals into the US Military Armed Forces is prohibited during the review period which ends on January 1, 2018, after that it is expected that the accession policy will continue to exclude openly transgender personnel from entering the armed forces.
"IMMEDIATE RELEASE No. NR-312-17
Aug. 29, 2017________________________________________
Statement by Secretary of Defense Jim Mattis on Military Service by Transgender Individuals
The Department of Defense has received the Presidential Memorandum, dated August 25, 2017, entitled “Military Service by Transgender Individuals.” The department will carry out the president’s policy direction, in consultation with the Department of Homeland Security. As directed, we will develop a study and implementation plan, which will contain the steps that will promote military readiness, lethality, and unit cohesion, with due regard for budgetary constraints and consistent with applicable law. The soon arriving senior civilian leadership of DOD will play an important role in this effort. The implementation plan will address accessions of transgender individuals and transgender individuals currently serving in the United States military.
Our focus must always be on what is best for the military’s combat effectiveness leading to victory on the battlefield. To that end, I will establish a panel of experts serving within the Departments of Defense and Homeland Security to provide advice and recommendations on the implementation of the president’s direction. Panel members will bring mature experience, most notably in combat and deployed operations, and seasoned judgment to this task. The panel will assemble and thoroughly analyze all pertinent data, quantifiable and non-quantifiable. Further information on the panel will be forthcoming.
Once the panel reports its recommendations and following my consultation with the secretary of Homeland Security, I will provide my advice to the president concerning of his policy direction. In the interim, current policy with respect to currently serving members will remain in place. I expect to issue interim guidance to the force concerning the president’s direction, including any necessary interim adjustments to procedures, to ensure the continued combat readiness of the force until our final policy on this subject is issued."
Background: Presidential memorandum dated August 25, 2017
"Presidential Memorandum for the Secretary of Defense and the Secretary of Homeland Security
MEMORANDUM FOR THE SECRETARY OF DEFENSE
THE SECRETARY OF HOMELAND SECURITY
SUBJECT: Military Service by Transgender Individuals
Section 1. Policy. (a) Until June 2016, the Department of Defense (DoD) and the Department of Homeland Security (DHS) (collectively, the Departments) generally prohibited openly transgender individuals from accession into the United States military and authorized the discharge of such individuals. Shortly before President Obama left office, however, his Administration dismantled the Departments' established framework by permitting transgender individuals to serve openly in the military, authorizing the use of the Departments' resources to fund sex-reassignment surgical procedures, and permitting accession of such individuals after July 1, 2017. The Secretary of Defense and the Secretary of Homeland Security have since extended the deadline to alter the currently effective accession policy to January 1, 2018, while the Departments continue to study the issue.
In my judgment, the previous Administration failed to identify a sufficient basis to conclude that terminating the Departments' longstanding policy and practice would not hinder military effectiveness and lethality, disrupt unit cohesion, or tax military resources, and there remain meaningful concerns that further study is needed to ensure that continued implementation of last year's policy change would not have those negative effects.
(b) Accordingly, by the authority vested in me as President and as Commander in Chief of the Armed Forces of the United States under the Constitution and the laws of the United States of America, including Article II of the Constitution, I am directing the Secretary of Defense, and the Secretary of Homeland Security with respect to the U.S. Coast Guard, to return to the longstanding policy and practice on military service by transgender individuals that was in place prior to June 2016 until such time as a sufficient basis exists upon which to conclude that terminating that policy and practice would not have the negative effects discussed above. The Secretary of Defense, after consulting with the Secretary of Homeland Security, may advise me at any time, in writing, that a change to this policy is warranted.
Sec. 2. Directives. The Secretary of Defense, and the Secretary of Homeland Security with respect to the U.S. Coast Guard, shall:
(a) maintain the currently effective policy regarding accession of transgender individuals into military service beyond January 1, 2018, until such time as the Secretary of Defense, after consulting with the Secretary of Homeland Security, provides a recommendation to the contrary that I find convincing; and
(b) halt all use of DoD or DHS resources to fund sex reassignment surgical procedures for military personnel, except to the extent necessary to protect the health of an individual who has already begun a course of treatment to reassign his or her sex.
Sec. 3. Effective Dates and Implementation. Section 2(a) of this memorandum shall take effect on January 1, 2018. Sections 1(b) and 2(b) of this memorandum shall take effect on March 23, 2018. By February 21, 2018, the Secretary of Defense, in consultation with the Secretary of Homeland Security, shall submit to me a plan for implementing both the general policy set forth in section 1(b) of this memorandum and the specific directives set forth in section 2 of this memorandum. The implementation plan shall adhere to the determinations of the Secretary of Defense, made in consultation with the Secretary of Homeland Security, as to what steps are appropriate and consistent with military effectiveness and lethality, budgetary constraints, and applicable law. As part of the implementation plan, the Secretary of Defense, in consultation with the Secretary of Homeland Security, shall determine how to address transgender individuals currently serving in the United States military. Until the Secretary has made that determination, no action may be taken against such individuals under the policy set forth in section 1(b) of this memorandum.
Sec. 4. Severability. If any provision of this memorandum, or the application of any provision of this memorandum, is held to be invalid, the remainder of this memorandum and other dissimilar applications of the provision shall not be affected.
Sec. 5. General Provisions. (a) Nothing in this memorandum shall be construed to impair or otherwise affect:
(i) the authority granted by law to an executive department or agency, or the head thereof; or
(ii) the functions of the Director of the Office of Management and Budget relating to budgetary, administrative, or legislative proposals.
(c) This memorandum is not intended to, and does not, create any right or benefit, substantive or procedural, enforceable at law or in equity by any party against the United States, its departments, agencies, or entities, its officers, employees, or agents, or any other person.
(d) The Secretary of Defense is authorized and directed to publish this memorandum in the Federal Register."
from whitehouse.gov/the-press-office/2017/08/25/presidential-memorandum-secretary-defense-and-secretary-homeland