Defense Secretary Jim Mattis has decided to delay until next year a decision on whether to move forward with a policy that allows transgender people to enlist in the military.

Transgender service members have been allowed to serve openly in the military since last year. But former Defense Secretary Ash Carter set a July 1 deadline for the four military services to write their own policies to allow them to accept new transgender troops.

"Secretary Mattis today approved a recommendation by the services to defer accessing transgender applicants into the military until Jan. 1, 2018," said Dana W. White, a Pentagon spokesperson, in a statement Friday night. "The services will review their accession plans and provide input on the impact to the readiness and lethality of our forces."

Military leaders had sent a request to Mattis last week asking him to delay implementation of the new policy for six months.

The leaders said the six-month delay would give the services time to see if transgender troops currently serving are facing issues and determine if changes are needed.

By listening to military leaders, Mattis decided not to follow a request by more than a dozen Democratic lawmakers who wrote to him this week urging "no further delay" in implementing the policy.