Secretary of Defense Ashton Carter has announced that transgender people will be allowed to openly serve in the US military.

“We have to have access to 100 percent of America’s population for our all-volunteer force to be able to recruit from among them the most highly qualified — and to retain them,” he said.

Trans recruits will be required to have concluded all expected medical treatments for the transition and demonstrate that they have “been stable in their preferred gender” for at least a year and a half. Final guidelines will be released later, and will answer questions on restroom usage, medical treatment and the proper ways to address trans troops.

Carter added that the guidelines will be reviewed and updated within two years.

The Pentagon has been implementing a number of changes on enlisted restrictions over the past five years, including allowing openly gay troops to serve and authorizing women to serve in combat roles.