Gender rights groups have vowed to fight against Donald Trump’s “transphobia masquerading as policy” after the President moved to ban most transgender troops from serving in the military.

Several legal challenges to Mr Trump’s initial ban, announced in July, are ongoing. At least four federal judges refusing to allow the ban on transgender troops to go into effect. Because of the injunctions, the Pentagon has been allowing transgender individuals to enlist since January.

Last week, Mr Trump approved a policy recommendation stating that “transgender persons who require or have undergone gender transition are disqualified from military service.” Transgender troops who are currently in the US military may remain in the ranks, the White House said.

The policy has outraged many advocate groups.

“What the White House has released tonight is transphobia masquerading as policy. This policy is not based on an evaluation of new evidence,” Joshua Block, a senior staff attorney at the American Civil Liberties Union’s LGBT and HIV Project, said in a statement.

“It is reverse-engineered for the sole purpose of carrying out President Trump’s reckless and unconstitutional ban, undermining the ability of transgender service members to serve openly and military readiness as a whole,” he added.

One of the forefronts of the legal fight is in California, where a federal judge rejected the Trump administration’s request to throw out a lawsuit against the ban. California’s attorney general, Xavier Becerra, said the state would “continue to vigorously defend the rights of transgender individuals”.

Lambda Legal and OutServe-SLDN, meanwhile, said they would seek a permanent injunction to block the ban before a federal judge in Seattle.

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The Justice Department said in a statement that it would defend the Pentagon’s authority to “implement personnel policies they have determined are necessary to best defend our nation” and would ask the courts to lift all related preliminary injunctions.

On Friday, the White House said retaining troops with a history or diagnosis of “gender dysphoria” – wanting to transition gender – “presents considerable risk to military effectiveness and lethality”.

Gender dysphoria was defined as “those who may require substantial medical treatment, including through medical drugs or surgery”.

The policy adopted recommendations that Mr Trump received last month from Defence Secretary Jim Mattis.

Mr Trump in July 2017 declared on Twitter that the US would not “accept or allow ... transgender individuals to serve in any capacity” in the military, reversing an Obama administration plan to allow transgender individuals to serve openly. The tweets surprised the Pentagon, which initiated a review of the policies.

In a memo to the President, Mr Mattis said there were “substantial risks” with allowing military personnel who seek to undertake a treatment to change their gender or who question their gender identity.

Mr Mattis said exempting those in the military from “well-established mental health, physical health and sex-based standards” applying to all service members could hurt “military effectiveness and lethality”. The policy does includes narrow exemptions allowing some transgender members to serve.