Jim Mattis, the current Secretary of Defence (Photo by Keith Lane/Getty Images)

The Secretary of Defense, Jim Mattis, is expected to give guidance to the White House to keep transgender troops.

Two US officials told the Washington Post that it is likely Mattis will break away from the president’s wishes to ban trans individuals from serving.

The Pentagon missed it’s deadline on February 21 to release new guidance on transgender troops.

Dana White, a spokesperson for Mattis, said on Thursday that the secretary had missed the deadline because of the complexities of the policy had to be considered.

Related: Trans man told he could not enlist in military because of his gender identity

“This is a complex issue, and the secretary is taking his time to consider the information he’s been given.

“It’s an important issues, and again, he sees all of his decisions through the lens of lethality,” White said.

Trump will be expected to speak about the policy after it is decided on, but he may not if Mattis goes against his wish to ban trans troops.

President Trump tweeted in July last year calling for trans troops to be banned from the US armed forces, claiming they were a burden on the military.

The claims sparked months of legal battle.

Related: Legal challenge attempts to kill off Trump’s transgender ban for good

A DC judge prevented Trump from blocking an already-written directive to actively permit the enrolment of transgender people.

In a memo written by Mattis in September, the Defence Secretary wrote that the new policy on trans troops would have to be “consistent with military effectiveness and lethality”.

Deployability is a top priority for Mattis and the Pentagon as they just announced a new policy which dictates that unless a service member is able to be deployed in 12 months or less, they will be kicked out.

A study which was commissioned by the Pentagon and carried out by RAND, a non-partisan survey company, found that having transgender troops would make a negligible impact on the readiness to deploy.

The study stated: “In terms of readiness, RAND estimates that 10 to 130 active component members each year could have reduced deployability as a result of gender transition-related treatments.

“This amount is negligible relative to the 102,500 nondeployable soldiers in the Army alone in 2015, 50,000 of them in the active component.”

Since Trump’s tweets announcing the proposed ban, interim guidance was put in place by the Pentagon to temporarily halt trans troops from being forced to leave the service.

The guidance also allowed trans troops to access medical treatment and on January 1, transgender people were allowed to enlist openly.