President Donald Trump has signed a memorandum that bans some transgender individuals from serving in the US military, but gives the armed forces latitude in implementing policies.
The memorandum said transgender individuals with a history of gender dysphoria are disqualified from military service "except under certain limited circumstances."
It defined such individuals as "those who may require substantial medical treatment, including through medical drugs or surgery."
The order added that the secretaries of defence and homeland security may exercise their authority to implement any appropriate policies concerning military service by transgender individuals.
Defense Secretary Jim Mattis has said that transgender people pose a risk to the effectiveness of the miitary. Source: AAP
The White House said Defence Secretary Jim Mattis had found that individuals with a history or diagnosis of gender dysphoria presented a risk to military effectiveness.
"This new policy will enable the military to apply well-established mental and physical health standards ... equally to all individuals who want to join and fight for the best military force the world has ever seen," it said.
Trump's decision is less restrictive than his initial comments in a July Twitter message saying he would prohibit transgender people from military service.
That blanket ban reversed former President Barack Obama's policy.
At the time, Trump said on Twitter, the military "cannot be burdened with the tremendous medical costs and disruption that transgender in the military would entail."
A number of federal judges have issued rulings blocking Trump's ban, saying it would probably violate the right, under the US Constitution, to equal protection under the law.
On Friday, the Pentagon reaffirmed that it would continue to comply with federal law.
In a February memorandum to the White House, Mattis had said transgender individuals with a history of gender dysphoria were disqualified from military service.
But he added that those currently serving could continue to serve if they had been diagnosed with gender dysphoria since Obama's policy took effect.
The memorandum said 8,980 service members reportedly identify as transgender, but only 937 active duty service members were diagnosed with gender dysphoria since June 30, 2016.
