On Thursday, Secretary of Defense Ash Carter announced that the ban on open service of transgender troops will be lifted, five years after a similar ban on the open service of gay men and women was formally ended by President Obama. The end of the ban is effective immediately, Carter said. “Implementation will begin today,” he said, promising a “step by step approach.”

“It’s the right thing to do,” said Carter. “And it’s another step in making sure we continue to recruit and retain qualified people.”

He cited the military’s changes in policies regarding the service of women and gay troops as proof that the transition could be made smoothly, saying “we do have experience in this kind of thing.” Changes in on-the-ground policies, training and other aspects of implementing the change will take place over the next year.

Almost exactly a year ago, Carter had promised to review the ban. In comments made at a press conference at the Penatgon, Carter said the study of the possible implications of lifting the ban had shown there would be “minimal readiness impacts” and “minimal” costs, including coverage of medical care related to transitioning. As of his comments, transgender military members can no longer be discharged from the military because of their gender identity, he said.

In a RAND Corporation study conducted during the last year on possible impacts, the authors estimated that about 2,500 of the 1.3 million active duty members are transgender, while a study by UCLA’s Williams Institute estimated the number to be 15,500, in addition to 134,300 veterans.

In his comments, Carter cited the “sea change” in perception and treatment of transgender people in broader society, building a case that ending the ban is not a jump of the gun. “The reality is that we have transgender service members serving in uniform today,” he said, “and I have a responsibility to them and to their commanders to provide them both with clear and more consistent guidelines.”

He argued that America’s all-volunteer force could not afford to categorically reject possible service members because of reasons “unrelated to a person’s qualification to serve.” This news came on the same day that the Williams Institute, which specializes in research on the LGBT population, published a study estimating that 0.6% of the population is transgender, amounting to 1.4 million Americans. That is double the estimate that institution made in a previous 2011 study.

“Although relatively few in number,” he said,” we’re talking about talented and trained Americans who are serving their country with honor and distinction.

Over the next 90 days, the Department of Defense will issue a training handbook for commanders and transgender service members, as well as guidance on providing medical care to transgender troops. The Department of Veterans Affairs, as first reported by TIME, has quietly proposed lifting a long-standing ban on the coverage of sex reassignment surgery, in a similar move. Both Carter and the V.A. said that more comprehensive coverage is in line with the latest medical research and consensus on effective standards of care for transgender people.

Over the next nine months, the entire service will undergo training related to the change, Carter said. And within a year, the military will begin to welcome new openly transgender military members. At least initially, those troops will be required to have finished all transition-related care deemed necessary by a medical professional and have “been stable” in their gender for a 18 months. That standard will be reviewed in two years, he added.

LGBT rights advocacy groups had grown impatient for news about the ban, as the review was initially set to take six months. But they were quick to applaud the move. “Allowing anyone who is willing and able to serve to do so without lying about who they are is a sound policy that reflects American values,” Mara Keisling, executive director of the National Center for Transgender Equality, said in a statement. “This is the right decision for the military and brings much needed certainty for thousands of currently serving soldiers who have put their lives on the line for their country, as well as for their units.”

In the final months of his presidency, Obama’s administration has made several moves in support of transgender rights and the LGBT community. “The entire Obama Administration wants you to know that we see you,” Attorney General Loretta Lynch said in announcing a lawsuit against North Carolina, which passed a law widely criticized as anti-transgender. “We stand with you. And we will do everything we can to protect you going forward. Please know that history is on your side.”

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Write to Katy Steinmetz at katy.steinmetz@time.com.