In laying out his reasons for moving on Wednesday to ban transgender people from serving in the U.S. military, President Donald Trump cited the "tremendous medical costs" associated with the policy.

His claim raises several immediate questions, such as exactly how much the Department of Defense spends on providing health care for transgender service members, as well as whether there are enough transgender people in the armed forces to move the needle on the department's annual $6 billion in health care spending on active-duty forces.

The answer? President Trump's assertion that permitting transgender people in the armed services entails major health care costs appears to be overblown, based on estimates from the think tank RAND, which was asked by the Department of Defense to study the issue last year. Health care costs for treating active members who want to transition to another gender would increase by between $2.4 million to $8.4 million annually, RAND found. That translates to 0.04 percent to 0.13 percent of the agency's annual spending on health care.

"Our study found that the number of U.S. transgender service members who are likely to seek transition-related care is so small that a change in policy will likely have a marginal impact on health care costs and the readiness of the force," the Rand researchers wrote.

Likewise, a 2015 study in the New England Journal of Medicine concluded that the health care costs related to transition for transgender service members "is too low to warrant consideration in the current policy debate." Its author estimated the costs at $5.6 million annually, or "little more than a rounding error."