WASHINGTON — The Pentagon’s current regulations banning transgender individuals from serving in the military are outdated, Defense Secretary Ashton Carter said Monday, ordering a six-month study aimed at formally ending one of the last gender- or sexuality-based barriers to military service.

Carter said he is creating a working group that will review the policies and determine if lifting the ban would have any impact on the military’s ability to be ready for battle. But he said the group will begin with the presumption transgender people should be able to serve openly “without adverse impact on military effectiveness and readiness, unless and except where objective, practical impediments are identified.”

The plan gives the services time to methodically work through the legal, medical and administrative issues and develop training to ease any transition.

“The Defense Department’s current regulations regarding transgender service members are outdated and are causing uncertainty that distracts commanders from our core missions,” Carter said.